Compositions and methods for antibodies targeting epo

ABSTRACT

The present invention relates to compositions and methods for the inhibition of EPO. The invention provides antibodies and antigen binding fragments thereof that bind to EPO and are able to inhibit EPO-dependent cell proliferation and/or EPO-dependent cell signaling.

BACKGROUND OF THE INVENTION

Diabetic retinopathy (DR) is the most common complication in patientswith diabetes. Diabetic macular edema (DME) can occur in any stage of DRand is the main cause of vision loss in patients with DR. The incidenceof DME after 10 years of follow-up has been reported to be 20.1% in Type1 diabetes, 25.4% in Type 2 insulin-dependent diabetes, and 13.9% inType 2 non-insulin-dependent diabetes (Klein et al. (1995) Ophthalmology102, 7-16). The ETDRS trial ((1985) Photocoagulation for DiabeticMacular Edema—Early Treatment Diabetic—Retinopathy Study Report. 1.Archives of Ophthalmology 103, 1796-1806), a pioneering study in DR,demonstrated that although laser photocoagulation therapy reduces therisk of moderate visual loss in DME eyes by ˜50% at 3 years, only a feweyes gain vision, and some eyes continue to experience vision loss evenafter intensive treatment. In recent years, advances in pharmacotherapyand ocular drug delivery have shown promise in the treatment of DME. TheRESTORE study, one of two pivotal Phase III trials in DME (Mitchell etal. (2011) Ophthalmology 118, 615-625) demonstrated that Lucentis® wassuperior to laser monotherapy. The mean change in best-corrected visualacuity (BCVA), which was the primary clinical endpoint, wassignificantly improved in the Lucentis® group (+6.1 letters for theLucentis® group vs. +0.8 letters for the laser group; p<0.0001). Similarbeneficial effects have been demonstrated with VEGF Trap-Eye (RegeneronInc. NY, USA) and Ozurdex® (dexamethasone intravitreal implant; AllerganInc., CA, USA) (Do et al. (2011) Ophthalmology 118, 1819-1826; Haller etal. (2010) Archives of Ophthalmology 128, 289-296). However, 16% ofOzurdex treated eyes developed increased intra-ocular pressure, a riskfor glaucoma.

Despite these new treatment options for DME, there remains a substantialunmet medical need. ˜25% of eyes in the Lucentis® pivotal trials did notgain any visual acuity after 12 months of treatment and ˜50% of eyes areleft with visual acuity of 20/40 or worse. Genome-wide associationstudies indicated that diabetics who are homozygous for anerythropoietin (Epo) promoter polymorphism (T) have a 2.17-fold higherrisk of developing proliferative DR (Tong et al. (2008) Proc. Natl.Acad. Sci. U.S.A 105, 6998-7003). Interestingly, people with the Tpromoter allele for Epo have approximately 7.5-fold higher vitrealconcentration of Epo compared to people with the G allele (Tong et al.(2008) Proc. Natl. Acad. Sci. U.S.A 105, 6998-7003).

There remains a need to develop an effective treatment for diabeticretinopathy, particularly DME to replace or supplement currenttreatments.

SUMMARY OF THE INVENTION

The invention relates to antibodies, or antigen binding fragments, asdescribed herein which bind Epo and/or Darbepoietin.

The isolated antibodies, or antigen binding fragments, described hereinbind Epo and/or Darbepoietin, with a K_(D) of less than or equal to 100pM. For example, the isolated antibodies or antigen binding fragmentsdescribed herein may bind to human Epo and/or Darbepoietin with a K_(D)of less than or equal to 50 pM, less than or equal to 40 pM, less thanor equal to 35 pM, less than or equal to 30 pM, less than or equal to 25pM, less than or equal to 20 pM, less than or equal to 15 pM, less thanor equal to 14 pM, less than or equal to 13 pM, less than or equal to 12pM, less than or equal to 11 pM, less than or equal to 10 pM. Morespecifically, the isolated antibodies or antigen binding fragmentsdescribed herein may also bind human Epo with a K_(D) of less than orequal to 35 pM, as measured by Biacore, or less than or equal to 6 pM,as measured by Solution Equilibrium Titration (SET). More specifically,the isolated antibodies or antigen binding fragments described hereinmay also bind Darbepoietin with a K_(D) of less than or equal to 24 pM,as measured by Biacore, or less than or equal to 4 pM, as measured bySET.

The present invention relates to an isolated antibody, or antigenbinding fragment thereof, that binds to human, cynomolgus, mouse and/orrat Epo. The invention also relates to an isolated antibody, or antigenbinding fragment thereof, that binds a conformational epitope comprisingamino acids selected from human Epo Helix D and Loop A-B. The inventionfurther relates to an isolated antibody, or antigen binding fragmentthereof, that binds a conformational epitope comprising amino acidsselected from human Epo Helix D, Loop A-B and Helix A. In particularaspects of the invention, the isolated antibodies, or antigen bindingfragments thereof, may bind to the D Helix domain of Epo (amino acids138-162 of Human Epo; SEQ ID NO: 88). In other aspects, the isolatedantibodies, or antigen binding fragments described herein may bind theLoop A-B domain (amino acids 27-55 of Human Epo; SEQ ID NO: 89). Inother aspects the isolated antibodies, or antigen binding fragmentsdescribed herein may bind the Loop A-B domain (amino acids 27-55 ofHuman Epo; SEQ ID NO: 89) and Helix A (amino acids 4-26 of Human Epo;SEQ ID NO: 86). In further aspects of the invention, the isolatedantibodies, or antigen binding fragments described herein may bind the DHelix domain of Epo (amino acids 138-162 of Human Epo; SEQ ID NO: 88),and the Loop A-B domain (amino acids 27-55 of Human Epo; SEQ ID NO: 89).In still further aspects of the invention, the isolated antibodies, orantigen binding fragments described herein may bind the D Helix domainof Epo (amino acids 138-162 of Human Epo; SEQ ID NO: 88), and Helix A(amino acids 4-26 of Human Epo; SEQ ID NO: 86). In still further aspectsof the invention, the isolated antibodies, or antigen binding fragmentsdescribed herein may bind the D Helix domain of Epo (amino acids 138-162of Human Epo; SEQ ID NO: 88), the Loop A-B domain (amino acids 27-55 ofHuman Epo; SEQ ID NO: 89) and Helix A (amino acids 4-26 of Human Epo;SEQ ID NO: 86).

The present invention also relates to an isolated antibody, or antigenbinding fragment thereof, that binds a confirmational epitope on Epocomprising amino acid residues Thr44, Lys45, Val46, Asn47, Phe48, Tyr49,Ala50, Lys52, Arg53, Asn147, Arg150, Gly151, Lys154, Leu155, Glu159, andArg162 of Human Epo (SEQ ID NO.81). The present invention furtherrelates to an isolated antibody, or antigen binding fragment thereof,that binds a confirmational epitope on Epo comprising amino acidsresidues Ser9, Gln13, Thr44, Lys45, Va146, Asn47, Phe48, Tyr49, Ala50,Lys52, Arg53, Asn147, Arg150, Gly151, Lys154, Leu155, Gly158, Glu159,and Arg162, of Human Epo (SEQ ID NO.81). The present invention stillfurther relates to relates to an isolated antibody, or antigen bindingfragment thereof, that binds a confirmational epitope on Epo comprisingamino acid residues Glu23, Asp43, Thr44, Lys45, Val46, Asn47, Phe48,Tyr49, Ala50, Lys52, Arg53, Arg131, Arg143, Asn147, Arg150, Gly151,Lys154, Leu155, Glu159, and Arg162 of Human Epo (SEQ ID NO.81).

The present invention also relates to an isolated antibody, or antigenbinding fragment thereof, that binds Epo and further competes forbinding with an antibody as described in Table 1. The present inventionalso further relates to an isolated antibody, or antigen bindingfragment thereof, that binds the same epitope as an antibody asdescribed in Table 1.

The present invention also relates to an isolated antibody, or antigenbinding fragment thereof, that binds Epo and has an isoelectric point(p1) greater than 8.2, greater than 8.3, greater than 8.4, greater than8.5 or greater than 9.0.

The isolated antibodies or antigen binding fragments described hereinmay also bind cynomolgus Epo, mouse Epo and/or rat Epo with a K_(D) ofless than or equal to 100 pM, less than or equal to 80 pM, less than orequal to 70 pM, less than or equal to 60 pM, less than or equal to 50pM, less than or equal to 40 pM, less than or equal to 35 pM, less thanor equal to 30 pM, less than or equal to 25 pM, less than or equal to 20pM, less than or equal to 15 pM, less than or equal to 10 pM, less thanor equal to 5 pM, less than or equal to 4 pM, less than or equal to 3pM, less than or equal to 2 pM, less than or equal to 1 pM. Morespecifically, the isolated antibodies or antigen binding fragmentsdescribed herein may also bind cynomolgus Epo, mouse Epo and/or rat Epowith a K_(D) of less than or equal to 80 pM, as measured by Biacore, orless than or equal to 40 pM, as measured by SET. More specifically, theisolated antibodies or antigen binding fragments described herein mayalso bind Cynomolgus Epo with a K_(D) of less than or equal to 80 pM, asmeasured by Biacore, or less than or equal to 8 pM, as measured by SET.More specifically, the isolated antibodies or antigen binding fragmentsdescribed herein may also bind mouse Epo with a K_(D) of less than orequal to 45 pM, as measured by Biacore, or less than or equal to 37 pM,as measured by SET. More specifically, the isolated antibodies orantigen binding fragments described herein may also bind rat Epo with aK_(D) of less than or equal to 57 pM, as measured by Biacore, or lessthan or equal to 13 pM, as measured by SET.

The binding affinity of isolated antibodies and antigen bindingfragments described herein can be determined by SET. Methods for SET areknown in the art and are described in further detail below.Alternatively, binding affinity of the isolated antibodies, orfragments, described herein can be determined by Biacore assay. Methodsfor Biacore kinetic assays are known in the art and are described infurther detail below.

The isolated antibodies and antigen binding fragments described hereincan be used to inhibit Epo-dependent cell proliferation with an IC₅₀ ofless than or equal to 350 pM, less than or equal to 300 pM, less than orequal to 250 pM, less than or equal to 200 pM, less than or equal to 190pM, less than or equal to 180 pM, less than or equal to 175 pM, lessthan or equal to 170 pM, less than or equal to 160 pM, less than orequal to 150 pM, less than or equal to 125 pM, less than or equal to 115pM, less than or equal to 110 pM, less than or equal to 100 pM, lessthan or equal to 90 pM, or less than or equal to 80 pM. Morespecifically, an isolated antibody or antigen binding fragment thereofas described herein can inhibit Epo-dependent cell proliferation asmeasured by an in vitro Ba/F3-EpoR cell proliferation assay with an IC₅₀of less than or equal to 338 pM, less than or equal to 183 pM, less thanor equal to 175 pM, less than or equal to 174 pM, less than or equal to145 pM, less than or equal to 112 pM, less than or equal to 89 pM, orless than or equal to 74 pM.

The isolated antibodies and antigen binding fragments described hereincan be used to inhibit Epo-dependent cell proliferation in B-cells. Morespecifically, the isolated antibodies and antigen binding fragmentsdescribed herein can be used to inhibit Epo-dependent cell proliferationin mouse B-cells. For example, an isolated antibody or antigen bindingfragment thereof can inhibit Epo-dependent cell proliferation asmeasured by an in vitro Ba/F3-EpoR cell proliferation assay with an IC₅₀of less than or equal to 350 pM, less than or equal to 300 pM, less thanor equal to 250 pM, less than or equal to 200 pM, less than or equal to175 pM, less than or equal to 150 pM, less than or equal to 125 pM, lessthan or equal to 115 pM, less than or equal to 110 pM, less than orequal to 100 pM, less than or equal to 90 pM, or less than or equal to80 pM. More specifically, an isolated antibody or antigen bindingfragment thereof as described herein can inhibit Epo-dependent cellproliferation as measured by an in vitro Ba/F3-EpoR cell proliferationassay with an IC₅₀ of less than or equal to 338 pM, less than or equalto 174 pM, less than or equal to 112 pM, or less than or equal to 74 pM.

The isolated antibodies and antigen binding fragments described hereincan be used to inhibit Epo-dependent cell proliferation of humanB-cells. For example, an isolated antibody or antigen binding fragmentthereof can inhibit Epo-dependent cell proliferation, as measured by anin vitro F36E cell proliferation assay, with an ICso of less than orequal to 200 pM, less than or equal to 190 pM, less than or equal to 180pM, less than or equal to 170 pM, less than or equal to 160 pM, lessthan or equal to 150 pM, less than or equal to 125 pM, less than orequal to 100 pM, or less than or equal to 90 pM. More specifically, anisolated antibody or antigen binding fragment thereof as describedherein can inhibit Epo-dependent cell proliferation as measured by an invitro F36E cell proliferation assay with an IC₅₀ of less than or equalto 183 pM, less than or equal to 175 pM, less than or equal to 145 pM,or less than or equal to 89 pM.

The isolated antibodies, or antigen binding fragments thereof, may alsoblock Epo binding to the Epo receptor and/or prevent Epo binding to acell surface.

Another aspect of the invention includes an isolated antibody, orantigen binding fragment thereof, that specifically binds to human,cynomolgus, mouse and/or rat Epo. In a further aspect, the isolatedantibody, or antigen binding fragment, competes for binding with anantibody, or antigen binding fragment, described in Table 1.

The isolated antibodies, or antigen binding fragments thereof, asdescribed herein can be monoclonal antibodies, human or humanizedantibodies, chimeric antibodies, single chain antibodies, Fab fragments,Fv fragments, F(ab′)2 fragments, or ScFv fragments, and/or IgG isotypes.

The isolated antibodies, or antigen binding fragments thereof, asdescribed herein can also include a framework in which an amino acid hasbeen substituted into the antibody framework from the respective humanVH or VL germline sequences.

Another aspect of the invention includes an isolated antibody or antigenbinding fragment thereof having the full heavy and light chain sequencesof Fabs described in Table 1. More specifically, the isolated antibodyor antigen binding fragment thereof can have the heavy and light chainsequences of Fab NVS1, NVS2, NVS3, or NVS4.

A further aspect of the invention includes an isolated antibody orantigen binding fragment thereof having the heavy and light chainvariable domain sequences of Fabs described in Table 1. Morespecifically, the isolated antibody or antigen binding fragment thereofcan have the heavy and light chain variable domain sequence of Fab NVS1(SEQ ID NOs 13 and 14, respectively), NVS2 (SEQ ID NOs 33 and 34,respectively), NVS3 (SEQ ID NOs 53 and 54, respectively), or NVS4 (SEQID NOs 73 and 74, respectively).

The invention also relates to an isolated antibody or antigen bindingfragment thereof that includes a heavy chain CDR1 selected from thegroup consisting of SEQ ID NOs 1, 21, 41, and 61; a heavy chain CDR2selected from the group consisting of SEQ ID NOs: 2, 22, 42, and 62; anda heavy chain CDR3 selected from the group consisting of SEQ ID NOs: 3,23, 43, and 63, wherein the isolated antibody or antigen bindingfragment thereof binds to human Epo. In another aspect, such isolatedantibody or antigen binding fragment thereof further includes a lightchain CDR1 selected from the group consisting of SEQ ID NOs: 4, 24, 44,and 64; a light chain CDR2 selected from the group consisting of SEQ IDNOs 5, 25, 45, and 65; and a light chain CDR3 selected from the groupconsisting of SEQ ID NOs 6, 26, 46, and 66.

The invention also relates to an isolated antibody or antigen bindingfragment thereof that includes a light chain CDR1 selected from thegroup consisting of SEQ ID NOs: 4, 24, 44, and 64; a light chain CDR2selected from the group consisting of SEQ ID NOs 5, 25, 45, and 65; anda light chain CDR3 selected from the group consisting of SEQ ID NOs 6,26, 46, and 66, wherein the isolated antibody or antigen bindingfragment thereof binds to human Epo.

The invention also relates to an isolated antibody or antigen bindingfragment thereof that binds Epo having HCDR1, HCDR2, HCDR3 and LCDR1,LCDR2, LCDR3, wherein HCDR1, HCDR2, HCDR3 comprises SEQ ID NOs: 1, 2, 3,and LCDR1, LCDR2, LCDR3 comprises SEQ ID NOs: 4, 5, 6; or HCDR1, HCDR2,HCDR3 comprises SEQ ID NOs: 21, 22, 23, and LCDR1, LCDR2, LCDR3comprises SEQ ID NOs: 24, 25, 26; or HCDR1, HCDR2, HCDR3 comprises SEQID NOs: 41, 42, 43, and LCDR1, LCDR2, LCDR3 comprises SEQ ID NOs: 44,45, 46; or HCDR1, HCDR2, HCDR3 comprises SEQ ID NOs: 61, 62, 63, andLCDR1, LCDR2, LCDR3 comprises SEQ ID NOs: 64, 65, 66.

The invention also relates to an antibody or antigen binding fragmenthaving HCDR1, HCDR2, and HCDR3 of the variable heavy chain of SEQ ID NO:13, 33, 53 or 73, and the LCDR1, LCDR2 and LCDR3 of the variable lightchain of SEQ ID NO: 14, 34, 54 or 74, as defined by Chothia. In anotheraspect of the invention the antibody or antigen binding fragment mayhave the HCDR1, HCDR2, and HCDR3 of the heavy chain variable domainsequence of SEQ ID NO: 13, 33, 53 or 73, and the LCDR1, LCDR2 and LCDR3of the light chain variable domain sequence of SEQ ID NO: 14, 34, 54 or74, as defined by Kabat.

In one aspect of the invention the isolated antibody or antigen bindingfragment thereof includes a heavy chain variable domain (VH) sequenceselected from the group consisting of SEQ ID NOs: 13, 33, 53 and 73. Theisolated antibody or antigen binding fragment further can comprise alight chain variable domain (VL) sequence wherein the heavy chainvariable domain and light chain variable domain combine to form anantigen binding site for Epo. In particular the light chain variabledomain sequence can be selected from SEQ ID NOs: 14, 34, 54 and 74wherein said isolated antibody or antigen binding fragment thereof bindsEpo.

The invention also relates to an isolated antibody or antigen bindingfragment thereof that includes a light chain variable domain sequenceselected from the group consisting of SEQ ID NOs: 14, 34, 54 and 74,wherein said isolated antibody or antigen binding fragment thereof bindsto human Epo. The isolated antibody or antigen binding fragment mayfurther comprise a heavy chain variable domain sequence wherein thelight chain variable domain and heavy chain variable domain combine toform and antigen binding site for Epo.

In particular, the isolated antibody or antigen binding fragment thereofthat binds Epo, may have heavy and light chain variable domainscomprising the sequences of SEQ ID NOs: 13 and 14; 33 and 34; 53 and 54;or 73 and 74, respectively.

The invention further relates to an isolated antibody or antigen bindingfragment thereof, that includes a heavy chain variable domain having atleast 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to asequence selected from the group consisting of SEQ ID NOs:13, 33, 53,and 73, wherein said antibody binds to Epo. In one aspect, the isolatedantibody or antigen binding fragment thereof also includes a light chainvariable domain having at least 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99%sequence identity to a sequence selected from the group consisting ofSEQ ID NOs: 14, 34, 54, and 74. In a further aspect of the invention,the isolated antibody or antigen binding fragment has an HCDR1, HCDR2,HCDR3, LCDR1, LCDR2 and LCDR3 as defined by Kabat and as described inTable 1. It is also contemplated that the HCDR1, HCDR2, HCDR3, LCDR1,LCDR2 and LCDR3 may be defined by Chothia and as described in Table 1.

The invention also relates to an isolated antibody or antigen bindingfragment thereof, having a light chain variable domain having at least80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to a sequenceselected from the group consisting of SEQ ID NOs: 14, 34, 54, and 74,wherein said antibody binds Epo.

In another aspect of the invention, the isolated antibody, or antigenbinding fragment thereof, that binds to Epo may have a heavy chaincomprising the sequence of SEQ ID NO: 15, 35, 55, or 75. The isolatedantibody can also include a light chain that can combine with the heavychain to form an antigen binding site to human Epo. In particular, thelight chain may have a sequence comprising SEQ ID NO: 16, 36, 56, or 76.In particular, the isolated antibody or antigen binding fragment thereofthat binds Epo, may have a heavy chain and a light chain comprising thesequences of SEQ ID NOs: 15 and 16; 35 and 36; 55 and 56; or 75 and 76,respectively.

The invention still further relates to an isolated antibody or antigenbinding fragment thereof that includes a heavy chain having at least80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to a sequenceselected from the group consisting of SEQ ID NOs: 15, 35, 55, and 75,wherein said antibody binds to Epo. In one aspect, the isolated antibodyor antigen binding fragment thereof also includes a light chain havingat least 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to asequence selected from the group consisting of SEQ ID NOs 16, 36, 56,and 76.

The invention still further relates to an isolated antibody or antigenbinding fragment thereof that includes a light chain having at least80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to a sequenceselected from the group consisting of SEQ ID NOs 16, 36, 56, and 76,wherein said antibody binds Epo.

The invention also relates to compositions comprising the isolatedantibody, or antigen binding fragment thereof, as described herein. Aswell as, antibody compositions in combination with a pharmaceuticallyacceptable carrier. Specifically, the invention further includespharmaceutical compositions comprising an antibody or antigen bindingfragment thereof of Table 1, such as, for example antibody NVS1, NVS2,NVS3 or NVS4. The invention also relates to pharmaceutical compositionscomprising a combination of two or more of the isolated antibodies orantigen binding fragments thereof of Table 1.

The invention also relates to an isolated nucleic acid sequence encodingthe variable heavy chain having a sequence selected from SEQ ID NO: 13,33, 53 and 73. In particular the nucleic acid has a sequence at least80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to a sequenceselected from the group consisting of SEQ ID NOs: 17, 37, 57, and 77. Ina further aspect of the invention the sequence is SEQ ID NOs: 17, 37,57, or 77.

The invention also relates to an isolated nucleic acid sequence encodingthe variable light chain having a sequence selected from SEQ ID NO: 14,34, 54 and 74. In particular the nucleic acid has a sequence at least80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequence identity to a sequenceselected from the group consisting of SEQ ID NOs: 18, 38, 58, and 78. Ina further aspect of the invention the sequence is SEQ ID NOs: 18, 38,58, or 78.

The invention also relates to an isolated nucleic acid comprising asequence encoding a polypeptide that includes a light chain variabledomain having at least 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% sequenceidentity to a sequence selected from the group consisting of SEQ ID NOs:18, 38, 58, and 78.

The invention also relates to a vector that includes one or more of thenucleic acid molecules described herein.

The invention also relates to an isolated host cell that includes one ormore of the nucleic acid molecules or vectors described herein. Theinvention also relates to an isolated host cell that includes arecombinant DNA sequence encoding a heavy chain of the antibodydescribed above, and a second recombinant DNA sequence encoding a lightchain of the antibody described above, wherein said DNA sequences areoperably linked to a promoter and are capable of being expressed in thehost cell. It is contemplated that the antibody can be a humanmonoclonal antibody. It is also contemplated that the host cell is anon-human mammalian cell, for example a CHO cell.

The invention also relates to a method of inhibiting Epo-dependent cellproliferation wherein the method includes the step of contacting Epo(e.g., contacting Epo in a subject) with an effective amount of acomposition comprising the isolated antibody or antigen bindingfragments thereof described herein; in particular, the composition cancomprise the antibody NVS1, NVS2, NVS3, or NVS4. In one aspect, themethod comprises contacting a cell (e.g., a cell comprising Epo) with acomposition coprising the isolated antibody or antigen binding fragmentthereof as described herein. The invention also relates to a compositioncomprising an isolated antibody or antigen binding fragment thereof asdescribed herein for use to inhibit Epo-dependent cell proliferation ina subject. It is contemplated that the cell is a human cell. It isfurther contemplated that the cell is in a subject. It is alsocontemplated that the cell is in the eye of the subject. It is stillfurther contemplated that the subject is human.

The invention also relates to a method of inhibiting Epo-dependent cellsignalling wherein the method includes the step of contacting Epo withan effective amount of a composition comprising the isolated antibody orantigen binding fragments thereof described herein to prevent Epo frominteracting with a receptor on a cell surface. In one aspect, the methodcomprises contacting a cell comprising Epo with a composition coprisingthe isolated antibody or antigen binding fragment thereof as describedherein. The invention also relates to a composition comprising anisolated antibody or antigen binding fragment thereof as describedherein for use to inhibit Epo-dependent cell signalling in a subject. Itis contemplated that the cell is a human cell. It is furthercontemplated that the cell is in a subject. It is also contemplated thatthe cell is in the eye of the subject. It is still further contemplatedthat the subject is human.

The invention also relates to a method of inhibiting Epo-dependent cellproliferation or signalling wherein the method includes the step ofcontacting Epo with an effective amount of a composition comprising theisolated antibody or antigen binding fragments thereof described hereinto prevent Epo from interacting with a receptor on a cell surface. It iscontemplated that the cell is a B cell. It is contemplated that the cellis a human cell.

The invention also relates to a method of inhibiting Epo binding to theEpo receptor wherein the method includes the step of contacting Epo(e.g., contacting Epo in a subject) with an effective amount of acomposition comprising the isolated antibody or antigen bindingfragments thereof described herein; in particular, the composition cancomprise the antibody NVS1, NVS2, NVS3, or NVS4. The invention alsorelates to a composition comprising an isolated antibody or antigenbinding fragment thereof as described herein for use to inhibit Epobinding to the Epo receptor on a cell of a subject; in particular, thecomposition can comprise the antibody NVS1, NVS2, NVS3, or NVS4. It iscontemplated that the cell is a human cell. It is further contemplatedthat the cell is in a subject. It is also contemplated that the cell isin the eye of the subject. It is still further contemplated that thesubject is human.

The invention still further relates to a method of inhibiting Epobinding to a cell wherein the method includes the step of contacting Epo(e.g., in a subject) with an effective amount of a compositioncomprising the isolated antibody or antigen binding fragments thereofdescribed herein; in particular, the composition can comprise theantibody NVS1, NVS2, NVS3, or NVS4. In one aspect, the method comprisescontacting a cell (e.g., a cell comprising Epo) with a compositioncoprising the isolated antibody or antigen binding fragment thereof asdescribed herein. The invention still further relates to a compositioncomprising an isolated antibody or antigen binding fragment thereof asdescribed herein for use to inhibit Epo binding to a cell in a subject.In one aspect, it is contemplated that the cell is a human cell. It isfurther contemplated that the cell is in a subject. It is alsocontemplated that the cell is in the eye of the subject. It is stillfurther contemplated that the subject is human.

The invention also relates to a method of treating macular edema in asubject, wherein the method includes the step of administering to thesubject an effective amount of a composition comprising the antibody orantigen binding fragments thereof described herein; in particular, thecomposition can comprise the antibody NVS1, NVS2, NVS3, or NVS4. Theinvention also relates to a composition comprising an antibody orantigen binding fragment thereof as described herein to treat macularedema in a subject. In one aspect, macular edema is associated withretinal vascular disease. It is contemplated that the retinal vasculardisease associated with the macular edema can include diabeticretinopathy, diabetic macular edema, proliferative diabetic retinopathy,non-proliferative diabetic retinopathy, age-related maculardegeneration, retinal vein occlusion, multifocal choroiditis, myopicchoroidal neovascularization, or retinopathy of prematurity. It is alsocontemplated that the subject is human.

The invention also relates to a method of treating a condition ordisorder associated with retinal vascular disease in a subject, whereinthe method includes the step of administering to the subject aneffective amount of a composition comprising the antibody or antigenbinding fragments thereof described herein; in particular, thecomposition can comprise the antibody NVS1, NVS2, NVS3, or NVS4. Theinvention also relates to a composition comprising an antibody orantigen binding fragment thereof as described herein to treat acondition or disorder associated with retinal vascular disease in asubject. In one aspect, it is contemplated that the condition ordisorder associated with retinal vascular disease is diabeticretinopathy. In another aspect, it is contemplated that the condition ordisorder is age-related macular degeneration. It is still furthercontemplated that the condition or disorder associated with retinalvascular disease can be retinal vein occlusion, multifocal choroiditis,myopic choroidal neovascularization, or retinopathy of prematurity. Itis also contemplated that the subject is human.

The invention also relates to a method of treating a condition ordisorder associated with diabetic retinopathy in a subject, wherein themethod includes the step of administering to the subject an effectiveamount of a composition comprising the antibody or antigen bindingfragments thereof as described herein; in particular, the compositioncan comprise the antibody NVS1, NVS2, NVS3, or NVS4. The invention alsorelates to a composition comprising an antibody or antigen bindingfragment thereof as described herein to treat a condition or disorderassociated with diabetic retinopathy in a subject. It is contemplatedthat the subject is human.

The invention also relates to a method of treating a condition ordisorder associated with macular edema in a subject, wherein the methodincludes the step of administering to the subject an effective amount ofa composition comprising the antibody or antigen binding fragmentsthereof as described herein; in particular, the composition can comprisethe antibody NVS1, NVS2, NVS3, or NVS4. The invention also relates to acomposition comprising an antibody or antigen binding fragment thereofas described herein to treat a condition or disorder associated withmacular edema in a subject. It is further contemplated that thecondition or disorder associated with macular edema is diabetic macularedema. It is further contemplated that the subject is human.

The invention also relates to a method of treating proliferativediabetic retinopathy in a subject, wherein the method includes the stepof administering to the subject an effective amount of a compositioncomprising the antibody or antigen binding fragments thereof describedherein; in particular, the composition can comprise the antibody NVS1,NVS2, NVS3, or NVS4. The invention also relates to a compositioncomprising an antibody or antigen binding fragment thereof as describedherein to treat proliferative diabetic retinopathy in a subject. It isfurther contemplated that the composition is administered to the eye ofthe subject wherein the composition decreases retinal vein dilation,decreases vascular leakage and/or increases blood flow in the eye. It isfurther contemplated that the subject is human.

Any of the foregoing isolated antibodies or antigen binding fragmentsthereof may be a monoclonal antibody or antigen binding fragmentthereof.

Definitions

Unless defined otherwise, all technical and scientific terms used hereinhave the same meaning as commonly understood by those of ordinary skillin the art to which this invention pertains.

The term “antibody” as used herein means a whole antibody and anyantigen binding fragment (i.e., “antigen-binding portion”) or singlechain thereof. A whole antibody is a glycoprotein comprising at leasttwo heavy (H) chains and two light (L) chains inter-connected bydisulfide bonds. Each heavy chain is comprised of a heavy chain variableregion (abbreviated herein as VH) and a heavy chain constant region. Theheavy chain constant region is comprised of three domains, CH1, CH2 andCH3. Each light chain is comprised of a light chain variable region(abbreviated herein as VL) and a light chain constant region. The lightchain constant region is comprised of one domain, CL. The VH and VLregions can be further subdivided into regions of hypervariability,termed complementarity determining regions (CDR), interspersed withregions that are more conserved, termed framework regions (FR). Each VHand VL is composed of three CDRs and four FRs arranged fromamino-terminus to carboxy-terminus in the following order: FR1, CDR1,FR2, CDR2, FR3, CDR3, FR4. The variable regions of the heavy and lightchains contain a binding domain that interacts with an antigen. Theconstant regions of the antibodies may mediate the binding of theimmunoglobulin to host tissues or factors, including various cells ofthe immune system (e.g., effector cells) and the first component (Clq)of the classical complement system.

The term “antigen binding portion” or “antigen binding fragment” of anantibody, as used herein, refers to one or more fragments of an intactantibody that retain the ability to specifically bind to a given antigen(e.g., Erythropoietin: Epo). Antigen binding functions of an antibodycan be performed by fragments of an intact antibody. Examples of bindingfragments encompassed within the term antigen binding portion or antigenbinding fragment of an antibody include a Fab fragment, a monovalentfragment consisting of the VL, VH, CL and CH1 domains; a F(ab)₂fragment, a bivalent fragment comprising two Fab fragments linked by adisulfide bridge at the hinge region; an Fd fragment consisting of theVH and CH1 domains; an Fv fragment consisting of the VL and VH domainsof a single arm of an antibody; a single domain antibody (dAb) fragment(Ward et al., 1989 Nature 341:544-546), which consists of a VH domain ora VL domain; and an isolated complementarity determining region (CDR).

Furthermore, although the two domains of the Fv fragment, VL and VH, arecoded for by separate genes, they can be joined, using recombinantmethods, by an artificial peptide linker that enables them to be made asa single protein chain in which the VL and VH regions pair to formmonovalent molecules (known as single chain Fv (scFv); see, e.g., Birdet al., 1988 Science 242:423-426; and Huston et al., 1988 Proc. Natl.Acad. Sci. 85:5879-5883). Such single chain antibodies include one ormore antigen binding portions or fragments of an antibody. Theseantibody fragments are obtained using conventional techniques known tothose of skill in the art, and the fragments are screened for utility inthe same manner as are intact antibodies.

Antigen binding fragments can also be incorporated into single domainantibodies, maxibodies, minibodies, intrabodies, diabodies, triabodies,tetrabodies, v-NAR and bis-scFv (see, e.g., Hollinger and Hudson, 2005,Nature Biotechnology, 23, 9, 1126-1136). Antigen binding portions ofantibodies can be grafted into scaffolds based on polypeptides such asFibronectin type III (Fn3) (see U.S. Pat. No. 6,703,199, which describesfibronectin polypeptide monobodies).

Antigen binding fragments can be incorporated into single chainmolecules comprising a pair of tandem Fv segments (VH-CH1-VH-CH1) which,together with complementary light chain polypeptides, form a pair ofantigen binding regions (Zapata et al., 1995 Protein Eng.8(10):1057-1062; and U.S. Pat. No. 5,641,870).

As used herein, the term “affinity” refers to the strength ofinteraction between antibody and antigen at single antigenic sites.Within each antigenic site, the variable region of the antibody “arm”interacts through weak non-covalent forces with antigen at numeroussites; the more interactions, the stronger the affinity. As used herein,the term “high affinity” for an antibody or antigen binding fragmentthereof (e.g.: a Fab fragment) generally refers to an antibody, orantigen binding fragment, having a KD of 10⁻⁹M or less.

The term “amino acid” refers to naturally occurring and synthetic aminoacids, as well as amino acid analogs and amino acid mimetics thatfunction in a manner similar to the naturally occurring amino acids.Naturally occurring amino acids are those encoded by the genetic code,as well as those amino acids that are later modified, e.g.,hydroxyproline, γ-carboxyglutamate, and O-phosphoserine. Amino acidanalogs refer to compounds that have the same basic chemical structureas a naturally occurring amino acid, i.e., an alpha carbon that is boundto a hydrogen, a carboxyl group, an amino group, and an R group, e.g.,homoserine, norleucine, methionine sulfoxide, methionine methylsulfonium. Such analogs have modified R groups (e.g., norleucine) ormodified peptide backbones, but retain the same basic chemical structureas a naturally occurring amino acid. Amino acid mimetics refers tochemical compounds that have a structure that is different from thegeneral chemical structure of an amino acid, but that functions in amanner similar to a naturally occurring amino acid.

The term “binding specificity” as used herein refers to the ability ofan individual antibody combining site to react with only one antigenicdeterminant.

The phrase “specifically (or selectively) binds” to an antibody (e.g.,an Epo-binding antibody) refers to a binding reaction that isdeterminative of the presence of a cognate antigen (e.g., a human Epo orcynomolgus Epo) in a heterogeneous population of proteins and otherbiologics. The phrases “an antibody recognizing an antigen” and “anantibody specific for an antigen” are used interchangeably herein withthe term “an antibody which binds specifically to an antigen”.

The term “condition or disorder associated with retinal vasculardisease” refers to conditions, disorders or diseases in which the retinadegenerates or becomes dysfunctional. This includes diabetic retinopathy(DR), diabetic macular edema (DME), proliferative diabetic retinopathy(PDR), non-proliferative diabetic retinopathy (NPDR), age-relatedmacular degeneration (AMD), retinal vein occlusion (RVO), multifocalchoroiditis, myopic choroidal neovascularization, or retinopathy ofprematurity. Anatomic characteristics of retinal vascular disease thatmay be treated by Epo inhibition include macular edema, venous dilation,vessel tortuosity, vascular leakage as measured by fluoresceinangiography, retinal hemorrhage, and microvascular anomalies (e.g.microaneurysm, cotton-wool spots, IRMA), capillary dropout, leukocyteadhesion, retinal ischemia, neovascularization of the optic disk,neovascularization of the posterior pole, iris neovascularization,intraretinal hemorrhage, vitreous hemorrhage, macular scar, subretinalfibrosis, and retinal fibrosis.

The term “condition or disorder associated with diabetic retinopathy”refers to conditions in which the retina degenerates or becomesdysfunctional, as a consequence of effects of diabetes mellitus (Type 1or Type 2) on retinal vasculature, retinal metabolism, retinal pigmentepithelium, the blood-retinal barrier, or ocular levels of advancedglycation end products (AGEs), aldose reductase activity, glycosylatedhemoglobin, and protein kinase C. Visual loss in patients with diabeticretinopathy can be a result of retinal ischemia, macular edema, vascularleakage, vitreous hemorrhage, or direct effects of elevated glucoselevels on retinal neurons. Anatomic characteristics of diabeticretinopathy that may be treated by Epo inhibition include microaneurysm,cotton wool spots, venous dilation, macular edema, intra-retinalmicrovascular abnormalities (IRMA), intra-retinal hemorrhage, vascularproliferation, neovascularization of the disk, rubeosis, and retinalischemia. “Diabetic macular edema” occurs in a subject with diabeticretinopathy and can occur at any stage of the disease.

The term “condition or disorder associated with macular edema”, refersto conditions or disorders in which swelling or thickening of the maculaoccurs as a result of retinal blood vessels leaking fluid, “macularedema”. Macular edema occurs in, and is often a complication of, retinalvascular disease. Specific conditions or disorders associated withmacular edema include, diabetic retinopathy, diabetic macular edema,proliferative diabetic retinopathy, non-proliferative diabeticretinopathy, age-related macular degeneration, retinal vein occlusion,multifocal choroiditis, myopic choroidal neovascularization, orretinopathy of prematurity. Treatment of macular edema by the inhibitionof Epo can be determined by funduscopic examination, optical coherencetomography, and improved visual acuity.

The term “chimeric antibody” is an antibody molecule in which (a) theconstant region, or a portion thereof, is altered, replaced or exchangedso that the antigen binding site (variable region) is linked to aconstant region of a different or altered class, effector functionand/or species, or an entirely different molecule which confers newproperties to the chimeric antibody, e.g., an enzyme, toxin, hormone,growth factor, drug, etc.; or (b) the variable region, or a portionthereof, is altered, replaced or exchanged with a variable region havinga different or altered antigen specificity. For example, a mouseantibody can be modified by replacing its constant region with theconstant region from a human immunoglobulin. Due to the replacement witha human constant region, the chimeric antibody can retain itsspecificity in recognizing the antigen while having reduced antigenicityin human as compared to the original mouse antibody.

The terms “Epo protein” or “Epo antigen” or “EPO” or “Epo” are usedinterchangeably, and refer to the erythropoietin protein in differentspecies. For example, human Epo has the sequence as set out in Table 1:SEQ ID NO: 81. Examples of Epo proteins from other species are providedin Table 1, SEQ ID NOs: 82, 83, 84 or 85. The protein sequences forhuman, cynomolgus, mouse, rat, and rabbit Epo are publicly available anddescribed in Table 1. Human Epo can also be hyperglycosylated.Hyperglycosylated Epo is also know in the art as “darbepoietin” and canbe obtained from various sources including, LEK Pharmacueticals.

The term “conservatively modified variant” applies to both amino acidand nucleic acid sequences. With respect to particular nucleic acidsequences, conservatively modified variants refers to those nucleicacids which encode identical or essentially identical amino acidsequences, or where the nucleic acid does not encode an amino acidsequence, to essentially identical sequences. Because of the degeneracyof the genetic code, a large number of functionally identical nucleicacids encode any given protein. For instance, the codons GCA, GCC, GCGand GCU all encode the amino acid alanine. Thus, at every position wherean alanine is specified by a codon, the codon can be altered to any ofthe corresponding codons described without altering the encodedpolypeptide. Such nucleic acid variations are “silent variations,” whichare one species of conservatively modified variations. Every nucleicacid sequence herein which encodes a polypeptide also describes everypossible silent variation of the nucleic acid. One of skill willrecognize that each codon in a nucleic acid (except AUG, which isordinarily the only codon for methionine, and TGG, which is ordinarilythe only codon for tryptophan) can be modified to yield a functionallyidentical molecule. Accordingly, each silent variation of a nucleic acidthat encodes a polypeptide is implicit in each described sequence.

For polypeptide sequences, “conservatively modified variants” includeindividual substitutions, deletions or additions to a polypeptidesequence which result in the substitution of an amino acid with achemically similar amino acid. Conservative substitution tablesproviding functionally similar amino acids are well known in the art.Such conservatively modified variants are in addition to and do notexclude polymorphic variants, interspecies homologs, and alleles of theinvention. The following eight groups contain amino acids that areconservative substitutions for one another: 1) Alanine (A), Glycine (G);2) Aspartic acid (D), Glutamic acid (E); 3) Asparagine (N), Glutamine(Q); 4) Arginine (R), Lysine (K); 5) Isoleucine (I), Leucine (L),Methionine (M), Valine (V); 6) Phenylalanine (F), Tyrosine (Y),Tryptophan (VV); 7) Serine (S), Threonine (T); and 8) Cysteine (C),Methionine (M) (see, e.g., Creighton, Proteins (1984)). In someembodiments, the term “conservative sequence modifications” are used torefer to amino acid modifications that do not significantly affect oralter the binding characteristics of the antibody containing the aminoacid sequence.

The term “epitope” means a protein determinant capable of specificbinding to an antibody. Epitopes usually consist of chemically activesurface groupings of molecules such as amino acids or sugar side chainsand usually have specific three dimensional structural characteristics,as well as specific charge characteristics. Conformational andnon-conformational epitopes are distinguished in that the binding to theformer but not the latter is lost in the presence of denaturingsolvents.

The term “human antibody”, as used herein, is intended to includeantibodies having variable regions in which both the framework and CDRregions are derived from sequences of human origin. Furthermore, if theantibody contains a constant region, the constant region also is derivedfrom such human sequences, e.g., human germline sequences, or mutatedversions of human germline sequences. The human antibodies of theinvention may include amino acid residues not encoded by human sequences(e.g., mutations introduced by random or site-specific mutagenesis invitro or by somatic mutation in vivo).

The term “human monoclonal antibody” refers to antibodies displaying asingle binding specificity which have variable regions in which both theframework and CDR regions are derived from human sequences. In oneembodiment, the human monoclonal antibodies are produced by hybridomaswhich include (i) a B cell obtained from a transgenic non-human animal,e.g., a transgenic mouse, having a genome comprising a human heavy chaintransgene and a light chain transgene (ii) fused to an immortalizedcell.

A “humanized” antibody is an antibody that retains the reactivity of anon-human antibody while being less immunogenic in humans. This can beachieved, for instance, by retaining the non-human CDR regions andreplacing the remaining parts of the antibody with their humancounterparts (i.e., the constant region as well as the frameworkportions of the variable region). See, e.g., Morrison et al., Proc.Natl. Acad. Sci. USA, 81:6851-6855, 1984; Morrison and 0i, Adv.Immunol., 44:65-92, 1988; Verhoeyen et al., Science, 239:1534-1536,1988; Padlan, Molec. Immun., 28:489-498, 1991; and Padlan, Molec.Immun., 31:169-217, 1994. Other examples of human engineering technologyinclude, but are not limited to Xoma technology disclosed in U.S. Pat.No. 5,766,886.

The terms “identical” or 100% percent “identity,” in the context of twoor more nucleic acids or polypeptide sequences, refer to two or moresequences or subsequences that are the same. Two sequences are“substantially identical” if two sequences have a specified percentageof amino acid residues or nucleotides that are the same (i.e., 60%identity, optionally 65%, 70%, 75%, 80%, 85%, 90%, 95%, or 99% identityover a specified region, or, when not specified, over the entiresequence), when compared and aligned for maximum correspondence over acomparison window, or designated region as measured using one of thefollowing sequence comparison algorithms or by manual alignment andvisual inspection. Optionally, the identity exists over a region that isat least about 50 nucleotides (or 10 amino acids) in length, or morepreferably over a region that is 100 to 500 or 1000 or more nucleotides(or 20, 50, 200 or more amino acids) in length.

For sequence comparison, typically one sequence acts as a referencesequence, to which test sequences are compared. When using a sequencecomparison algorithm, test and reference sequences are entered into acomputer, subsequence coordinates are designated, if necessary, andsequence algorithm program parameters are designated. Default programparameters can be used, or alternative parameters can be designated. Thesequence comparison algorithm then calculates the percent sequenceidentities for the test sequences relative to the reference sequence,based on the program parameters.

A “comparison window”, as used herein, includes reference to a segmentof any one of the number of contiguous positions selected from the groupconsisting of from 20 to 600, usually about 50 to about 200, moreusually about 100 to about 150 in which a sequence may be compared to areference sequence of the same number of contiguous positions after thetwo sequences are optimally aligned. Methods of alignment of sequencesfor comparison are well known in the art. Optimal alignment of sequencesfor comparison can be conducted, e.g., by the local homology algorithmof Smith and Waterman (1970) Adv. Appl. Math. 2:482c, by the homologyalignment algorithm of Needleman and Wunsch, J. Mol. Biol. 48:443, 1970,by the search for similarity method of Pearson and Lipman, Proc. Nat'l.Acad. Sci. USA 85:2444, 1988, by computerized implementations of thesealgorithms (GAP, BESTFIT, FASTA, and TFASTA in the Wisconsin GeneticsSoftware Package, Genetics Computer Group, 575 Science Dr., Madison,Wis.), or by manual alignment and visual inspection (see, e.g., Brent etal., Current Protocols in Molecular Biology, John Wiley & Sons, Inc.(Ringbou ed., 2003)).

Two examples of algorithms that are suitable for determining percentsequence identity and sequence similarity are the BLAST and BLAST 2.0algorithms, which are described in Altschul et al., Nuc. Acids Res.25:3389-3402, 1977; and Altschul et al., J. Mol. Biol. 215:403-410,1990, respectively. Software for performing BLAST analyses is publiclyavailable through the National Center for Biotechnology Information.This algorithm involves first identifying high scoring sequence pairs(HSPs) by identifying short words of length W in the query sequence,which either match or satisfy some positive-valued threshold score Twhen aligned with a word of the same length in a database sequence. T isreferred to as the neighborhood word score threshold (Altschul et al.,supra). These initial neighborhood word hits act as seeds for initiatingsearches to find longer HSPs containing them. The word hits are extendedin both directions along each sequence for as far as the cumulativealignment score can be increased. Cumulative scores are calculatedusing, for nucleotide sequences, the parameters M (reward score for apair of matching residues; always >0) and N (penalty score formismatching residues; always <0). For amino acid sequences, a scoringmatrix is used to calculate the cumulative score. Extension of the wordhits in each direction are halted when: the cumulative alignment scorefalls off by the quantity X from its maximum achieved value; thecumulative score goes to zero or below, due to the accumulation of oneor more negative-scoring residue alignments; or the end of eithersequence is reached. The BLAST algorithm parameters W, T, and Xdetermine the sensitivity and speed of the alignment. The BLASTN program(for nucleotide sequences) uses as defaults a wordlength (W) of 11, anexpectation (E) or 10, M=5, N=−4 and a comparison of both strands. Foramino acid sequences, the BLASTP program uses as defaults a wordlengthof 3, and expectation (E) of 10, and the BLOSUM62 scoring matrix (seeHenikoff and Henikoff, Proc. Natl. Acad. Sci. USA 89:10915, 1989)alignments (B) of 50, expectation (E) of 10, M=5, N=−4, and a comparisonof both strands.

The BLAST algorithm also performs a statistical analysis of thesimilarity between two sequences (see, e.g., Karlin and Altschul, Proc.Natl. Acad. Sci. USA 90:5873-5787, 1993). One measure of similarityprovided by the BLAST algorithm is the smallest sum probability (P(N)),which provides an indication of the probability by which a match betweentwo nucleotide or amino acid sequences would occur by chance. Forexample, a nucleic acid is considered similar to a reference sequence ifthe smallest sum probability in a comparison of the test nucleic acid tothe reference nucleic acid is less than about 0.2, more preferably lessthan about 0.01, and most preferably less than about 0.001.

The percent identity between two amino acid sequences can also bedetermined using the algorithm of E. Meyers and W. Miller (Comput. Appl.Biosci., 4:11-17, 1988) which has been incorporated into the ALIGNprogram (version 2.0), using a PAM120 weight residue table, a gap lengthpenalty of 12 and a gap penalty of 4. In addition, the percent identitybetween two amino acid sequences can be determined using the Needlemanand Wunsch (J. Mol, Biol. 48:444-453, 1970) algorithm which has beenincorporated into the GAP program in the GCG software package (availableon the world wide web at gcg.com), using either a Blossom 62 matrix or aPAM250 matrix, and a gap weight of 16, 14, 12, 10, 8, 6, or 4 and alength weight of 1, 2, 3, 4, 5, or 6.

Other than percentage of sequence identity noted above, anotherindication that two nucleic acid sequences or polypeptides aresubstantially identical is that the polypeptide encoded by the firstnucleic acid is immunologically cross reactive with the antibodiesraised against the polypeptide encoded by the second nucleic acid, asdescribed below. Thus, a polypeptide is typically substantiallyidentical to a second polypeptide, for example, where the two peptidesdiffer only by conservative substitutions. Another indication that twonucleic acid sequences are substantially identical is that the twomolecules or their complements hybridize to each other under stringentconditions, as described below. Yet another indication that two nucleicacid sequences are substantially identical is that the same primers canbe used to amplify the sequence.

The term “inhibit (or inhibits) Epo-dependent cell proliferation” refersto the ability of an anti-Epo antibody to interfere with cell activation(e.g., cell signaling), replication and/or proliferation stimulatedand/or induced by Epo. Specifically, “inhibit” refers to a statisticallysignificant decrease (i.e., p<0.05) in Epo-dependent cell proliferation,or other parameter (e.g., Epo dependent cell signaling, angiogenesis),in a subject following contact with an anti-Epo antibody or fragmentthereof as described herein relative to a control. As used herein,“inhibit (or inhibits) Epo-dependent cell proliferation” can also referto a clinically relevant improvement in visual function or retinalanatomy following treatment with an anti-Epo antibody described hereinin a patient diagnosed with a condition or disorder associated withretinal vascular disease as described below.

As used herein, “inhibit (or inhibits) Epo dependent cell signaling”refers to the ability of an anti-Epo antibody described herein toproduce a statistically significant (i.e., p<0.05) decrease in theactivation of the intracellular signaling pathways stimulated or inducedby Epo.

The term “isolated antibody” refers to an antibody that is substantiallyfree of other antibodies having different antigenic specificities (e.g.,an isolated antibody that specifically binds Epo is substantially freeof antibodies that specifically bind antigens other than Epo). Anisolated antibody that specifically binds Epo may, however, havecross-reactivity to other antigens. Moreover, an isolated antibody maybe substantially free of other cellular material and/or chemicals.

The term “isotype” refers to the antibody class (e.g., IgM, IgE, IgGsuch as IgG1 or IgG4) that is provided by the heavy chain constantregion genes. Isotype also includes modified versions of one of theseclasses, where modifications have been made to alter the Fc function,for example, to enhance or reduce effector functions or binding to Fcreceptors. Isotype also refers to the antibody class (e.g., kappa,lambda) that is provided by the light-chain constant regions.

The term “Kassoc” or “Ka”, as used herein, is intended to refer to theassociation rate of a particular antibody-antigen interaction, whereasthe term “Kdis” or “Kd,” as used herein, is intended to refer to thedissociation rate of a particular antibody-antigen interaction. The term“K_(D)”, as used herein, is intended to refer to the dissociationconstant, which is obtained from the ratio of Kd to Ka (i.e. Kd/Ka) andis expressed as a molar concentration (M). K_(D) values for antibodiescan be determined using methods well established in the art. Methods fordetermining the K_(D) of an antibody include measuring surface plasmonresonance using a biosensor system such as a Biacore® system, ormeasuring affinity in solution by solution equilibrium titration (SET).

The terms “monoclonal antibody” or “monoclonal antibody composition” asused herein refer to a preparation of antibody molecules of singlemolecular composition. A monoclonal antibody composition displays asingle binding specificity and affinity for a particular epitope.

The term “nucleic acid” is used herein interchangeably with the term“polynucleotide” and refers to deoxyribonucleotides or ribonucleotidesand polymers thereof in either single- or double-stranded form. The termencompasses nucleic acids containing known nucleotide analogs ormodified backbone residues or linkages, which are synthetic, naturallyoccurring, and non-naturally occurring, which have similar bindingproperties as the reference nucleic acid, and which are metabolized in amanner similar to the reference nucleotides. Examples of such analogsinclude, without limitation, phosphorothioates, phosphoramidates, methylphosphonates, chiral-methyl phosphonates, 2-O-methyl ribonucleotides,peptide-nucleic acids (PNAs).

Unless otherwise indicated, a particular nucleic acid sequence alsoimplicitly encompasses conservatively modified variants thereof (e.g.,degenerate codon substitutions) and complementary sequences, as well asthe sequence explicitly indicated. Specifically, as detailed below,degenerate codon substitutions may be achieved by generating sequencesin which the third position of one or more selected (or all) codons issubstituted with mixed-base and/or deoxyinosine residues (Batzer et al.,Nucleic Acid Res. 19:5081, 1991; Ohtsuka et al., J. Biol. Chem.260:2605-2608, 1985; and Rossolini et al., Mol. Cell. Probes 8:91-98,1994).

The term “operably linked” refers to a functional relationship betweentwo or more polynucleotide (e.g., DNA) segments. Typically, the termrefers to the functional relationship of a transcriptional regulatorysequence to a transcribed sequence. For example, a promoter or enhancersequence is operably linked to a coding sequence if it stimulates ormodulates the transcription of the coding sequence in an appropriatehost cell or other expression system. Generally, promotertranscriptional regulatory sequences that are operably linked to atranscribed sequence are physically contiguous to the transcribedsequence, i.e., they are cis-acting. However, some transcriptionalregulatory sequences, such as enhancers, need not be physicallycontiguous or located in close proximity to the coding sequences whosetranscription they enhance.

As used herein, the term, “optimized” means that a nucleotide sequencehas been altered to encode an amino acid sequence using codons that arepreferred in the production cell or organism, generally a eukaryoticcell, for example, a cell of Pichia, a Chinese Hamster Ovary cell (CHO)or a human cell. The optimized nucleotide sequence is engineered toretain completely or as much as possible the amino acid sequenceoriginally encoded by the starting nucleotide sequence, which is alsoknown as the “parental” sequence. The optimized sequences herein havebeen engineered to have codons that are preferred in mammalian cells.However, optimized expression of these sequences in other eukaryoticcells or prokaryotic cells is also envisioned herein. The amino acidsequences encoded by optimized nucleotide sequences are also referred toas optimized.

The terms “polypeptide” and “protein” are used interchangeably herein torefer to a polymer of amino acid residues. The terms apply to amino acidpolymers in which one or more amino acid residue is an artificialchemical mimetic of a corresponding naturally occurring amino acid, aswell as to naturally occurring amino acid polymers and non-naturallyoccurring amino acid polymer. Unless otherwise indicated, a particularpolypeptide sequence also implicitly encompasses conservatively modifiedvariants thereof.

The term “recombinant human antibody”, as used herein, includes allhuman antibodies that are prepared, expressed, created or isolated byrecombinant means, such as antibodies isolated from an animal (e.g., amouse) that is transgenic or transchromosomal for human immunoglobulingenes or a hybridoma prepared therefrom, antibodies isolated from a hostcell transformed to express the human antibody, e.g., from atransfectoma, antibodies isolated from a recombinant, combinatorialhuman antibody library, and antibodies prepared, expressed, created orisolated by any other means that involve splicing of all or a portion ofa human immunoglobulin gene, sequences to other DNA sequences. Suchrecombinant human antibodies have variable regions in which theframework and CDR regions are derived from human germline immunoglobulinsequences. In certain embodiments, however, such recombinant humanantibodies can be subjected to in vitro mutagenesis (or, when an animaltransgenic for human Ig sequences is used, in vivo somatic mutagenesis)and thus the amino acid sequences of the VH and VL regions of therecombinant antibodies are sequences that, while derived from andrelated to human germline VH and VL sequences, may not naturally existwithin the human antibody germline repertoire in vivo.

The term “recombinant host cell” (or simply “host cell”) refers to acell into which a recombinant expression vector has been introduced. Itshould be understood that such terms are intended to refer not only tothe particular subject cell but to the progeny of such a cell. Becausecertain modifications may occur in succeeding generations due to eithermutation or environmental influences, such progeny may not, in fact, beidentical to the parent cell, but are still included within the scope ofthe term “host cell” as used herein.

The term “subject” includes human and non-human animals. Non-humananimals include all vertebrates (e.g.: mammals and non-mammals) such as,non-human primates (e.g.: cynomolgus monkey), sheep, dog, cow, chickens,amphibians, and reptiles. Except when noted, the terms “patient” or“subject” are used herein interchangeably. As used herein, the terms“cyno” or “cynomolgus” refer to the cynomolgus monkey (Macacafascicularis).

As used herein, the term “treating” or “treatment” of any disease ordisorder (e.g., retinal vascular disease, diabetic retinopathy, macularedema) refers in one embodiment, to ameliorating the disease or disorder(i.e., slowing or arresting or reducing the development of the diseaseor at least one of the clinical symptoms thereof). In another embodiment“treating” or “treatment” refers to alleviating or ameliorating at leastone physical parameter including those which may not be discernible bythe patient. In yet another embodiment, “treating” or “treatment” refersto modulating the disease or disorder, either physically, (e.g.,stabilization of a discernible symptom), physiologically, (e.g.,stabilization of a physical parameter), or both. In yet anotherembodiment, “treating” or “treatment” refers to preventing or delayingthe onset or development or progression of the disease or disorder.“Prevention” as it relates to indications described herein, including,conditions or disorders associated with retinal vascular disease,conditions or disorders associated with diabetic retinopathy, and/orconditions or disorders associated with macular edema, means any actionthat prevents or slows a worsening in visual function, retinal anatomy,retinal vascular disease parameter, diabetic retinopathy diseaseparameter, and/or macular edema disease parameter, as described below,in a patient at risk for said worsening. More specifically, “treatment”of conditions or disorders associated with retinal vascular disease,conditions or disorders associated with diabetic retinopathy, and/orconditions or disorders associated with macular edema means any actionthat results in, or is contemplated to result in, the improvement orpreservation of visual function and/or retinal anatomy. Methods forassessing treatment and/or prevention of disease are known in the artand described herein below.

The term “vector” is intended to refer to a polynucleotide moleculecapable of transporting another polynucleotide to which it has beenlinked. One type of vector is a “plasmid”, which refers to a circulardouble stranded DNA loop into which additional DNA segments may beligated. Another type of vector is a viral vector, such as anadeno-associated viral vector (AAV, or AAV2), wherein additional DNAsegments may be ligated into the viral genome. Certain vectors arecapable of autonomous replication in a host cell into which they areintroduced (e.g., bacterial vectors having a bacterial origin ofreplication and episomal mammalian vectors). Other vectors (e.g.,non-episomal mammalian vectors) can be integrated into the genome of ahost cell upon introduction into the host cell, and thereby arereplicated along with the host genome. Moreover, certain vectors arecapable of directing the expression of genes to which they areoperatively linked. Such vectors are referred to herein as “recombinantexpression vectors” (or simply, “expression vectors”). In general,expression vectors of utility in recombinant DNA techniques are often inthe form of plasmids. In the present specification, “plasmid” and“vector” may be used interchangeably as the plasmid is the most commonlyused form of vector. However, the invention is intended to include suchother forms of expression vectors, such as viral vectors (e.g.,replication defective retroviruses, adenoviruses and adeno-associatedviruses), which serve equivalent functions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1. Shows that EPO induces vessel dilation in the central retina.

FIG. 2. Shows that an anti-EPO Fab neutralizes EPO in rabbit eyes.

FIG. 3. Shows that an anti-EPO Fab neutralizes EPO in rabbit eyes.

DETAILED DESCRIPTION

The present invention is based, in part, on the discovery of antibodymolecules that specifically bind to Epo. The invention relates to bothfull IgG format antibodies as well as antigen binding fragments thereof,such as Fab fragments (e.g., see antibodies NVS1, NVS2, NVS3 and NVS4).

Accordingly, the present invention provides antibodies that specificallybind to Epo (e.g., human Epo, cynomolgus Epo, rat Epo, and mouse Epo),pharmaceutical compositions, production methods, and methods of use ofsuch antibodies and compositions.

Epo Antibodies & Antigen Binding Fragments

The present invention provides antibodies that specifically bind to Epo.In some embodiments, the present invention provides antibodies thatspecifically bind to human, cynomolgus, rat and/or mouse Epo, as well ashuman-hyperglycosylated Epo (darbepoietin). Antibodies of the inventioninclude, but are not limited to, the human monoclonal antibodies andFabs, isolated as described in the Examples.

The present invention provides antibodies that specifically bind an Epoprotein (e.g., human, cynomolgus, rat and/or mouse Epo), wherein theantibodies comprise a VH domain having an amino acid sequence of SEQ IDNO: 13, 33, 53 or 73. The present invention also provides antibodiesthat specifically bind to an Epo protein, wherein the antibodiescomprise a VH CDR having an amino acid sequence of any one of the VHCDRs listed in Table 1, infra. In particular, the invention providesantibodies that specifically bind to an Epo protein (e.g., human,cynomolgus, rat and/or mouse Epo), wherein the antibodies comprise (oralternatively, consist of) one, two, three, or more VH CDRs having anamino acid sequence of any of the VH CDRs listed in Table 1, infra.

The present invention provides antibodies that specifically bind to anEpo protein, said antibodies comprising a VL domain having an amino acidsequence of SEQ ID NO:14, 34, 54 or 74. The present invention alsoprovides antibodies that specifically bind to an Epo protein (e.g.,human, cynomolgus, rat and/or mouse Epo), said antibodies comprising aVL CDR having an amino acid sequence of any one of the VL CDRs listed inTable 1, infra. In particular, the invention provides antibodies thatspecifically bind to an Epo protein (e.g., human, cynomolgus, rat and/ormouse Epo), said antibodies comprising (or alternatively, consisting of)one, two, three or more VL CDRs having an amino acid sequence of any ofthe VL CDRs listed in Table 1, infra.

Other antibodies of the invention include amino acids that have beenmutated, yet have at least 80, 85, 90, 95, 96, 97, 98, or 99 percentidentity in the CDR regions with the CDR regions depicted in thesequences described in Table 1. In some embodiments, it includes mutantamino acid sequences wherein no more than 1, 2, 3, 4 or 5 amino acidshave been mutated in the CDR regions when compared with the CDR regionsdepicted in the sequence described in Table 1.

The present invention also provides nucleic acid sequences that encodeVH, VL, the full length heavy chain, and the full length light chain ofthe antibodies that specifically bind to an Epo protein (e.g., human,cynomolgus, rat and/or mouse Epo). Such nucleic acid sequences can beoptimized for expression in mammalian cells (for example, Table 1 showsthe optimized nucleic acid sequences for the heavy chain and light chainof antibodies of the invention).

TABLE 1 Examples of Epo Antibodies, Fabs and Epo Proteins Amino acidsequence or polynucleotide (PN)Sequence Identifier (SEQ.I.D.NO:) and sequence NVS1 CDRH1 Kabat 1 SYAISCDRH2 Kabat 2 GIDPISGFADYAQKFQG CDRH3 Kabat 3 ELYYPGTWMAVMAY CDRL1 Kabat4 SGDNIPEYYVH CDRL2 Kabat 5 RDNERPS CDRL3 Kabat 6 QVFDESSWHWVCDRH1 Chothia 7 GGTFRSY CDRH2 Chothia 8 DPISGF CDRH3 Chothia9 ELYYPGTWMAVMAY CDRL1 Chothia 10 DNIPEYY CDRL2 Chothia 11 RDNCDRL3 Chothia 12 FDESSWHW VH 13QVQLVQSGAEVKKPGSSVKVSCKASGGIFRSYAISWVRQAPGQGLEWMGGIDPISGFADYAQKFQGRVTITADESTSTAYMELSSLRSEDTAVYYCARELYYPG TWMAVMAYWGRGTLVTVSSVL 14 SYVLTQPPSVSVAPGKTARITCSGDNIPEYYVHWYQQKPGQAPVLVIYRDNERPSGIPERFSGSNSGNTATLTISRVEAGDEADYYCQVFDESSWHWVFGGGTK LTVL Heavy chain 15QVQLVQSGAEVKKPGSSVKVSCKASGGTFRSYAISWVRQAPGQGLEWMGGIDPISGFADYAQKFQGRVTITADESTSTAYMELSSLRSEDTAVYYCARELYYPGTWMAVMAYWGRGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNV NHKPSNTKVDKRVEPKSCLight chain 16 SYVLTQPPSVSVAPGKTARITCSGDNIPEYYVHWYQQKPGQAPVLVIYRDNERPSGIPERFSGSNSGNTATLTISRVEAGDEADYYCQVFDESSWHWVFGGGTKLTVLGQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTV APTECS PN encoding17 SEQ.I.D.NO: 13 caggtgcagctggtgcagtcaggcgccgaagtgaagaaacccggctctagcgtgaaggtgtcctgtaaagctagtggcggcacctttagatcctacgctattagctgggtgcgacaggctccaggccagggcctcgaatggatgggcggcatcgaccctattagcggcttcgccgactacgctcagaaatttcagggcagagtgactatcaccgccgacgagtctactagcaccgcctacatggaactgtctagcctgagatcagaggacaccgccgtgtactactgcgctagagagctgtactaccccggcacctggatggccgtgatggcctattggggcagaggcaccctggtgacagtgt cttct PN encoding18 SEQ.I.D.NO: 14 agctacgtgctgacccagccccctagcgtgtcagtggcccctggcaagaccgctagaatcacctgtagcggcgataacatccccgagtactacgtgcactggtatcagcagaagcccggccaggcccccgtgctggtgatctatagagataacgagcggcctagcggcatccccgagcggttttccggctctaatagcggcaacaccgctaccctgactatttcaagagtggaagccggcgacgaggccgactactactgtcaggtgttcgacgagtcttcatggcactgggtgttcggcggaggcaccaag ctgaccgtgctgPN encoding 19 SEQ.I.D.NO: 15caggtgcagctggtgcagtcaggcgccgaagtgaagaaacccggctctagcgtgaaggtgtcctgtaaagctagtggcggcacctttagatcctacgctattagctgggtgcgacaggctccaggccagggcctcgaatggatgggcggcatcgaccctattagcggcttcgccgactacgctcagaaatttcagggcagagtgactatcaccgccgacgagtctactagcaccgcctacatggaactgtctagcctgagatcagaggacaccgccgtgtactactgcgctagagagctgtactaccccggcacctggatggccgtgatggcctattggggcagaggcaccctggtgacagtgtcttctgctagcactaagggcccctccgtgttccctctggccccttccagcaagtctacctctggcggcaccgctgctctgggctgcctggtgaaggactacttccctgagcctgtgacagtgtcctggaactctggcgccctgacctccggcgtgcacaccttccctgccgtgctgcagtcctccggcctgtactccctgtcctccgtggtgacagtgccttcctccagcctgggcacccagacctatatctgcaacgtgaaccacaagccttccaacaccaaggtggacaagcgggtggagcctaagtcat gc PN encoding 20SEQ.I.D.NO: 16 agctacgtgctgacccagccccctagcgtgtcagtggcccctggcaagaccgctagaatcacctgtagcggcgataacatccccgagtactacgtgcactggtatcagcagaagcccggccaggcccccgtgctggtgatctatagagataacgagcggcctagcggcatccccgagcggttttccggctctaatagcggcaacaccgctaccctgactatttcaagagtggaagccggcgacgaggccgactactactgtcaggtgttcgacgagtcttcatggcactgggtgttcggcggaggcaccaagctgaccgtgctgggccagcctaaggctgcccccagcgtgaccctgttcccccccagcagcgaggagctgcaggccaacaaggccaccctggtgtgcctgatcagcgacttctacccaggcgccgtgaccgtggcctggaaggccgacagcagccccgtgaaggccggcgtggagaccaccacccccagcaagcagagcaacaacaagtacgccgccagcagctacctgagcctgacccccgagcagtggaagagccacaggtcctacagctgccaggtgacccacgagggcagcaccgtggaaaagaccgtg gccccaaccgagtgcagcNVS2 CDRH1_Kabat 21 SYWIG CDRH2_Kabat 22 WIDPYRSEIRYSPSFQG CDRH3_Kabat23 VSSEPFDS CDRL1_Kabat 24 SGDKLGDHYAY CDRL2_Kabat 25 DDSKRPSCDRL3_Kabat 26 ATWTFEGDYV CDRH1 Chothia 27 GYSFTSY CDRH2 Chothia28 DPYRSE CDRH3 Chothia 29 VSSEPFDS CDRL1 Chothia 30 DKLGDHYCDRL2 Chothia 31 DDS CDRL3 Chothia 32 WTFEGDY VH 33EVQLVQSGAEVKKPGESLKISCKGSGYSFTSYWIGWVRQMPGKGLEWMGWIDPYRSEIRYSPSFQGQVTISADKSISTAYLQWSSLKASDTAMYYCARVSSEPF DSWGQGTLVTVSS VL 34SYVLTQPPSVSVAPGKTARITCSGDKLGDHYAYWYQQKPGQAPVLVIYDDSKRPSGIPERFSGSNSGNTATLTISRVEAGDEADYYCATWTFEGDYVFGGGTKL TVL Heavy chain 35EVQLVQSGAEVKKPGESLKISCKGSGYSFTSYWIGWVRQMPGKGLEWMGWIDPYRSEIRYSPSFQGQVTISADKSISTAYLQWSSLKASDTAMYYCARVSSEPFDSWGQGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSN TKVDKRVEPKSCLight chain 36 SYVLTQPPSVSVAPGKTARITCSGDKLGDHYAYWYQQKPGQAPVLVIYDDSKRPSGIPERFSGSNSGNTATLTISRVEAGDEADYYCATWTFEGDYVFGGGTKLTVLGQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVA PTECS PN encoding37 SEQ.I.D.NO: 33 Gaggtgcagctggtgcagtcaggcgccgaagtgaagaagcccggcgagtcactgaagattagctgtaaaggctcaggctatagcttcactagctactggatcggctgggtgcgacagatgcccggcaagggcctggaatggatgggctggatcgacccctatagatcagagattaggtatagccctagctttcagggccaggtgacaattagcgccgataagtctattagcaccgcctacctgcagtggtctagcctgaaggctagtgacaccgctatgtactactgcgctagagtgtctagcgagcccttcgatagctggggccagggcaccctggtgacagtgtcttca PN encoding 38 SEQ.I.D.NO: 34agctacgtgctgacccagccccctagcgtgtcagtggcccctggcaagaccgctagaatcacctgtagcggcgataagctgggcgatcactacgcctactggtatcagcagaagcccggccaggcccccgtgctggtgatctacgacgactctaagcggcctagcggcatccccgagcggtttagcggctctaatagcggcaacaccgctaccctgactatttcaagagtggaagccggcgacgaggccgactactactgcgctacctggaccttcgagggcgactacgtgttcggcggaggcactaagctg accgtgctgPN encoding 39 SEQ.I.D.NO: 35gaggtgcagctggtgcagtcaggcgccgaagtgaagaagcccggcgagtcactgaagattagctgtaaaggctcaggctatagcttcactagctactggatcggctgggtgcgacagatgcccggcaagggcctggaatggatgggctggatcgacccctatagatcagagattaggtatagccctagctttcagggccaggtgacaattagcgccgataagtctattagcaccgcctacctgcagtggtctagcctgaaggctagtgacaccgctatgtactactgcgctagagtgtctagcgagcccttcgatagctggggccagggcaccctggtgacagtgtcttcagctagcactaagggcccctccgtgttccctctggccccttccagcaagtctacctctggcggcaccgctgctctgggctgcctggtgaaggactacttccctgagcctgtgacagtgtcctggaactctggcgccctgacctccggcgtgcacaccttccctgccgtgctgcagtcctccggcctgtactccctgtcctccgtggtgacagtgccttcctccagcctgggcacccagacctatatctgcaacgtgaaccacaagccttccaacaccaaggtggacaagcgggtggagcctaagtcatgc PN encoding 40 SEQ.I.D.NO: 36agctacgtgctgacccagccccctagcgtgtcagtggcccctggcaagaccgctagaatcacctgtagcggcgataagctgggcgatcactacgcctactggtatcagcagaagcccggccaggcccccgtgctggtgatctacgacgactctaagcggcctagcggcatccccgagcggtttagcggctctaatagcggcaacaccgctaccctgactatttcaagagtggaagccggcgacgaggccgactactactgcgctacctggaccttcgagggcgactacgtgttcggcggaggcactaagctgaccgtgctgggccagcctaaggctgcccccagcgtgaccctgttcccccccagcagcgaggagctgcaggccaacaaggccaccctggtgtgcctgatcagcgacttctacccaggcgccgtgaccgtggcctggaaggccgacagcagccccgtgaaggccggcgtggagaccaccacccccagcaagcagagcaacaacaagtacgccgccagcagctacctgagcctgacccccgagcagtggaagagccacaggtcctacagctgccaggtgacccacgagggcagcaccgtggaaaagaccgtggcc ccaaccgagtgcagcNVS3 CDRH1_Kabat 41 SNTAAWN CDRH2_Kabat 42 VIYYRSKWYNDYAVSVKSCDRH3_Kabat 43 SVPGGDPGLEHAFAY CDRL1_Kabat 44 SGDNLGTYYVE CDRL2_Kabat45 DDSDRPS CDRL3_Kabat 46 ASFASWSDSV CDRH1 Chothia 47 GDSVSSNTACDRH2 Chothia 48 YYRSKWY CDRH3 Chothia 49 SVPGGDPGLEHAFAY CDRL1 Chothia50 DNLGTYY CDRL2 Chothia 51 DDS CDRL3 Chothia 52 FASWSDS VH 53QVQLQQSGPGLVKPSQTLSLTCAISGDSVSSNTAAWNWIRQSPSRGLEWLGVIYYRSKWYNDYAVSVKSRITINPDTSKNQFSLQLNSVTPEDTAVYYCARSVPGGDPGLEHAFAYWGRGTLVTVSS VL 54SYVLTQPPSVSVAPGKTARITCSGDNLGTYYVEWYQQKPGQAPVLVIYDDSDRPSGIPERFSGSNSGNTATLTISRVEAGDEADYYCASFASWSDSVFGGGTKL TVL Heavy chain 55QVQLQQSGPGLVKPSQTLSLTCAISGDSVSSNTAAWNWIRQSPSRGLEWLGVIYYRSKWYNDYAVSVKSRITINPDTSKNQFSLQLNSVTPEDTAVYYCARSVPGGDPGLEHAFAYWGRGTLVTVSSASTKGPSVFPLAPSSKSTSGGTAALGCLVKDYFPEPVTVSWNSGALTSGVHTFPAVLQSSGLYSLSSVVTVPSSSLGTQTYICNVNHKPSNTKVDKRVEPKSC Light chain 56SYVLTQPPSVSVAPGKTARITCSGDNLGTYYVEWYQQKPGQAPVLVIYDDSDRPSGIPERFSGSNSGNTATLTISRVEAGDEADYYCASFASWSDSVFGGGTKLTVLGQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTVA PTECS PN encoding57 SEQ.I.D.NO: 53 Caggtgcagctgcagcagtcaggccctggcctggtgaaacctagtcagaccctgagcctgacctgcgctattagcggcgatagcgtgtcatctaacaccgccgcctggaactggattagacagtcacctagtagaggcctggaatggctgggcgtgatctactataggtctaagtggtacaacgactacgccgtgtcagtgaagtctaggatcactattaaccccgacacctctaagaatcagttcagcctgcagctgaatagcgtgacccccgaggacaccgccgtgtactactgcgctagatcagtgcctggcggcgaccccggcctggaacacgcctttgcctactggggcagaggcaccc tggtgacagtgtcttctPN encoding 58 SEQ.I.D.NO: 54agctacgtgctgacccagccccctagcgtgtcagtggcccctggcaagaccgctagaatcacctgtagcggcgataacctgggcacctactacgtggaatggtatcagcagaagcccggccaggcccccgtgctggtgatctacgacgatagcgatagacctagcggcatccccgagcggtttagcggctctaatagcggcaacaccgctaccctgactattagtagagtggaagccggcgacgaggccgactactactgcgctagtttcgctagttggagcgattcagtgttcggcggaggcactaagctg accgtgctgPN encoding 59 SEQ.I.D.NO: 55caggtgcagctgcagcagtcaggccctggcctggtgaaacctagtcagaccctgagcctgacctgcgctattagcggcgatagcgtgtcatctaacaccgccgcctggaactggattagacagtcacctagtagaggcctggaatggctgggcgtgatctactataggtctaagtggtacaacgactacgccgtgtcagtgaagtctaggatcactattaaccccgacacctctaagaatcagttcagcctgcagctgaatagcgtgacccccgaggacaccgccgtgtactactgcgctagatcagtgcctggcggcgaccccggcctggaacacgcctttgcctactggggcagaggcaccctggtgacagtgtcttctgctagcactaagggcccctccgtgttccctctggccccttccagcaagtctacctctggcggcaccgctgctctgggctgcctggtgaaggactacttccctgagcctgtgacagtgtcctggaactctggcgccctgacctccggcgtgcacaccttccctgccgtgctgcagtcctccggcctgtactccctgtcctccgtggtgacagtgccttcctccagcctgggcacccagacctatatctgcaacgtgaaccacaagccttccaacaccaaggtggacaagcgggtgg agcctaagtcatgcPN encoding 60 SEQ.I.D.NO: 56agctacgtgctgacccagccccctagcgtgtcagtggcccctggcaagaccgctagaatcacctgtagcggcgataacctgggcacctactacgtggaatggtatcagcagaagcccggccaggcccccgtgctggtgatctacgacgatagcgatagacctagcggcatccccgagcggtttagcggctctaatagcggcaacaccgctaccctgactattagtagagtggaagccggcgacgaggccgactactactgcgctagtttcgctagttggagcgattcagtgttcggcggaggcactaagctgaccgtgctgggccagcctaaggctgcccccagcgtgaccctgttcccccccagcagcgaggagctgcaggccaacaaggccaccctggtgtgcctgatcagcgacttctacccaggcgccgtgaccgtggcctggaaggccgacagcagccccgtgaaggccggcgtggagaccaccacccccagcaagcagagcaacaacaagtacgccgccagcagctacctgagcctgacccccgagcagtggaagagccacaggtcctacagctgccaggtgacccacgagggcagcaccgtggaaaagaccgtggcc ccaaccgagtgcagcNVS4 CDRH1_Kabat 61 SYYMS CDRH2_Kabat 62 WINPLKGNTNYAQKFQG CDRH3_Kabat63 EGMYFDI CDRL1_Kabat 64 SGDSIGDKYVY CDRL2_Kabat 65 DTNKRPS CDRL3_Kabat66 QSWDLDFNTYV CDRH1 Chothia 67 GYTFTSY CDRH2 Chothia 68 NPLKGNCDRH3 Chothia 69 EGMYFDI CDRL1 Chothia 70 DSIGDKY CDRL2 Chothia 71 DTNCDRL3 Chothia 72 WDLDFNTY VH 73QVQLVQSGAEVKKPGASVKVSCKASGYTFTSYYMSWVRQAPGQGLEWMGWINPLKGNTNYAQKFQGRVTMTRDTSISTAYMELSRLRSEDTAVYYCAREGMYFD IWGQGTLVTVSS VL 74SYELTQPLSVSVALGQTARITCSGDSIGDKYVYWYQQKPGQAPVLVIYDTNKRPSGIPERFSGSNSGNTATLTISRAQAGDEADYYCQSWDLDFNTYVFGGGTK LTVL Heavy chain 75gvglvgsgaevkkpgasvkvsckasgytftsyymswvrgapggglewmgwinplkgntnyagkfggrvtmtrdtsistaymelsrlrsedtavyycaregmyfdiwgggtivtvssastkgpsvfplapsskstsggtaalgclvkdyfpepvtvswnsgaltsgvhtfpavlgssglyslssvvtvpssslgtgtyicnvnhkpsnt kvdkrvepkscLight chain 76 SYELTQPLSVSVALGQTARITCSGDSIGDKYVYWYQQKPGQAPVLVIYDTNKRPSGIPERFSGSNSGNTATLTISRAQAGDEADYYCQSWDLDFNTYVFGGGTKLTVLGQPKAAPSVTLFPPSSEELQANKATLVCLISDFYPGAVTVAWKADSSPVKAGVETTTPSKQSNNKYAASSYLSLTPEQWKSHRSYSCQVTHEGSTVEKTV APTECS PN encoding77 SEQ.I.D.NO: 73 caggtgcagctggtgcagtcaggcgccgaagtgaagaaacccggcgctagtgtgaaggtgtcctgtaaagctagtggctacaccttcactagctactacatgagctgggtgcgacaggcccctggacagggcctggaatggatgggctggattaaccccctgaagggcaacactaactacgcccagaaattccagggccgagtgactatgactagggacactagcattagcaccgcctacatggaactgtctaggctgagatcagaggacaccgccgtgtactactgcgctagagaaggcatgtacttcgacatctggggccagggcaccctggtgacagtgtcttct PN encoding 78 SEQ.I.D.NO: 74agctacgagctgactcagcccctgagcgtgtcagtggccctgggacagaccgctagaatcacctgtagcggcgactctatcggcgacaaatacgtgtactggtatcagcagaagcccggccaggcccccgtgctggtgatctacgacactaacaagcggcctagcggcatccccgagcggtttagcggctctaatagcggcaacaccgctaccctgactattagtagggctcaggccggcgacgaggccgactactactgtcagtcatgggacctggacttcaacacctacgtgttcggcggaggcactaag ctgaccgtgctgPN encoding 79 SEQ.I.D.NO: 75caggtgcagctggtgcagtcaggcgccgaagtgaagaaacccggcgctagtgtgaaggtgtcctgtaaagctagtggctacaccttcactagctactacatgagctgggtgcgacaggcccctggacagggcctggaatggatgggctggattaaccccctgaagggcaacactaactacgcccagaaattccagggccgagtgactatgactagggacactagcattagcaccgcctacatggaactgtctaggctgagatcagaggacaccgccgtgtactactgcgctagagaaggcatgtacttcgacatctggggccagggcaccctggtgacagtgtcttctgctagcactaagggcccctccgtgttccctctggccccttccagcaagtctacctctggcggcaccgctgctctgggctgcctggtgaaggactacttccctgagcctgtgacagtgtcctggaactctggcgccctgacctccggcgtgcacaccttccctgccgtgctgcagtcctccggcctgtactccctgtcctccgtggtgacagtgccttcctccagcctgggcacccagacctatatctgcaacgtgaaccacaagccttccaacaccaaggtggacaagcgggtggagcctaagtcatgc PN encoding 80 SEQ.I.D.NO: 76agctacgagctgactcagcccctgagcgtgtcagtggccctgggacagaccgctagaatcacctgtagcggcgactctatcggcgacaaatacgtgtactggtatcagcagaagcccggccaggcccccgtgctggtgatctacgacactaacaagcggcctagcggcatccccgagcggtttagcggctctaatagcggcaacaccgctaccctgactattagtagggctcaggccggcgacgaggccgactactactgtcagtcatgggacctggacttcaacacctacgtgttcggcggaggcactaagctgaccgtgctgggccagcctaaggctgcccccagcgtgaccctgttcccccccagcagcgaggagctgcaggccaacaaggccaccctggtgtgcctgatcagcgacttctacccaggcgccgtgaccgtggcctggaaggccgacagcagccccgtgaaggccggcgtggagaccaccacccccagcaagcagagcaacaacaagtacgccgccagcagctacctgagcctgacccccgagcagtggaagagccacaggtcctacagctgccaggtgacccacgagggcagcaccgtggaaaagaccgtg gccccaaccgagtgcagcHuman Epo 81 NP_000790.2apprlicdsrvlerylleakeaenittgcaehcslnenitvpdtkvnfyawkrmevgggavevwgglallseavlrggallvnssgpweplglhvdkaysglrslttllralgagkeaisppdaasaaplrtitadtfrklfrvysnflrgklkly tgeacrtgdrCynomolgus Epo 82 Uniprot:apprlicdsrvlerylleakeaenvtmgcsescslnenitvpdtkvnfyawk P07865rmevgggavevwgglallseavlrggavlanssgpfeplglhmdkaisglrsittllralgageaislpdaasaaplrtitadtfcklfrvysnflrgklklyt geacrrgdr Mouse Epo83 NP_031968.1 apprlicdsrvleryileakeaenvtmgcaegprlsenitvpdtkvnfyawkrmeveegaievwgglsllseailgagallanssqppetlglhidkaisglrsltsllrvlgagkelmsppdttppaplrtltvdtfcklfrvyanflrgklkly tgevcrrgdr Rat Epo84 NP_058697.1 apprlicdsrvleryileakeaenvtmgcaegprlsenitvpdtkvnfyawkrmkveegavevwgglsllseailgagalganssqppeslglhidkaisglrsltsllrvlgagkelmsppdatgaaplrtltadtfcklfrvysnflrgklkly tgeacrrgdrRabbit Epo 85 NP_001075559.1Klatmgvrgrlallplallcllvlalglpvlgaparlicdsrvleryileakeaenvtmgcaegcslgenitvpdtkvnfhhwkkseagrhavevwgglallseamlrsgallanssglpetlgvhvdkaysglrsltsllralgvgkeaysppeaassaaplrtvaadticklfriysnflrgklklytgeacrrgdr Epo Helix A, 86amino acids 4- rlicdsrvlerylleakeaenit 26 of SEQ ID NO: 81 Epo Helix B,87 amino acids vgggavevwgglallseavlrggallvn 56-83 of SEQ ID NO: 81Epo Helix D, 88 amino acids frklfrvysnflrgklklytgeacr 138-162 of SEQID NO: 81 Epo Loop A-B, 89 amino acids tgcaehcslnenitvpdtkvnfawkrme27-55 of SEQ ID NO: 81

Other antibodies of the invention include those where the amino acids ornucleic acids encoding the amino acids have been mutated, yet have atleast 60, 65, 70, 75, 80, 85, 90, or 95 percent identity to thesequences described in Table 1. Some embodiments include mutant aminoacid sequences wherein no more than 1, 2, 3, 4 or 5 amino acids havebeen mutated in the variable regions when compared with the variableregions depicted in the sequence described in Table 1, while retainingsubstantially the same antigen binding activity.

Since each of these antibodies can bind to Epo, the VH, VL, full lengthlight chain, and full length heavy chain sequences (amino acid sequencesand the nucleotide sequences encoding the amino acid sequences) can be“mixed and matched” to create other Epo-binding antibodies of theinvention. Such “mixed and matched” Epo-binding antibodies can be testedusing the binding assays known in the art (e.g., ELISAs, and otherassays described in the Example section). When these chains are mixedand matched, a VH sequence from a particular VH/VL pairing should bereplaced with a structurally similar VH sequence. Likewise a full lengthheavy chain sequence from a particular full length heavy chain/fulllength light chain pairing should be replaced with a structurallysimilar full length heavy chain sequence. Likewise, a VL sequence from aparticular VH/VL pairing should be replaced with a structurally similarVL sequence. Likewise a full length light chain sequence from aparticular full length heavy chain/full length light chain pairingshould be replaced with a structurally similar full length light chainsequence. Accordingly, in one aspect, the invention provides an isolatedantibody or antigen binding region thereof having: a heavy chainvariable domain comprising an amino acid sequence selected from thegroup consisting of SEQ ID NOs: 13, 33, 53, and 73, and a light chainvariable domain comprising an amino acid sequence selected from thegroup consisting of SEQ ID NOs: 14, 34, 54 and 74 wherein the antibodyspecifically binds to Epo (e.g., human, cynomolgus, rat and/or mouseEpo). More specifically, in certain aspects, the invention provides anisolated antibody or antigen binding region thereof having a heavy chainvariable domain and a light chain variable domain comprising amino acidsequences selected from SEQ ID NOs: 13 and 14, respectively. In otherspecific aspects, the invention provides an isolated antibody or antigenbinding region thereof having a heavy chain variable domain and a lightchain variable domain comprising amino acid sequences selected from SEQID NOs: 33 and 34, respectively. In still other aspects, the inventionprovides an isolated antibody or antigen binding region thereof having aheavy chain variable domain and a light chain variable domain comprisingamino acid sequences selected from SEQ ID NOs: 53 and 54, respectively.In still other aspects, the invention provides an isolated antibody orantigen binding region thereof having a heavy chain variable domain anda light chain variable domain comprising amino acid sequences selectedfrom SEQ ID NOs: 73 and 74, respectively.

In another aspect, the invention provides (i) an isolated antibodyhaving: a full length heavy chain comprising an amino acid sequence thathas been optimized for expression in a mammalian cell selected from thegroup consisting of SEQ ID NOs: 15, 35, 55 and 75, and a full lengthlight chain comprising an amino acid sequence that has been optimizedfor expression in a mammalian cell selected from the group consisting ofSEQ ID NOs: 16, 36, 56, and 76; or (ii) a functional protein comprisingan antigen binding portion thereof. More specifically, in certainaspects, the invention provides an isolated antibody or antigen bindingregion thereof having a heavy chain and a light chain comprising aminoacid sequences selected from SEQ ID NOs: 15 and 16, respectively. Inother specific aspects, the invention provides an isolated antibody orantigen binding region thereof having a heavy chain and a light chaincomprising amino acid sequences selected from SEQ ID NOs: 35 and 36,respectively. In still other aspects, the invention provides an isolatedantibody or antigen binding region thereof having a heavy chain and alight chain comprising amino acid sequences selected from SEQ ID NOs: 55and 56, respectively. In still other aspects, the invention provides anisolated antibody or antigen binding region thereof having a heavy chainand a light chain comprising amino acid sequences selected from SEQ IDNOs: 75 and 76, respectively.

The terms “complementarity determining region,” and “CDR,” as usedherein refer to the sequences of amino acids within antibody variableregions which confer antigen specificity and binding affinity. Ingeneral, there are three CDRs in each heavy chain variable region(HCDR1, HCDR2, HCDR3) and three CDRs in each light chain variable region(LCDR1, LCDR2, LCDR3).

The precise amino acid sequence boundaries of a given CDR can be readilydetermined using any of a number of well-known schemes, including thosedescribed by Kabat et al. (1991), “Sequences of Proteins ofImmunological Interest,” 5th Ed. Public Health Service, NationalInstitutes of Health, Bethesda, MD (“Kabat” numbering scheme),Al-Lazikani et al., (1997) JMB 273,927-948 (“Chothia” numbering scheme).

For example, under Kabat, the CDR amino acid residues in the heavy chainvariable domain (VH) are numbered 31-35 (HCDR1), 50-65 (HCDR2), and95-102 (HCDR3); and the CDR amino acid residues in the light chainvariable domain (VL) are numbered 24-34 (LCDR1), 50-56 (LCDR2), and89-97 (LCDR3). Under Chothia the CDR amino acids in the VH are numbered26-32 (HCDR1), 52-56 (HCDR2), and 95-102 (HCDR3); and the amino acidresidues in VL are numbered 26-32 (LCDR1), 50-52 (LCDR2), and 91-96(LCDR3). By combining the CDR definitions of both Kabat and Chothia, theCDRs consist of amino acid residues 26-35 (HCDR1), 50-65 (HCDR2), and95-102 (HCDR3) in human VH and amino acid residues 24-34 (LCDR1), 50-56(LCDR2), and 89-97 (LCDR3) in human VL.

In another aspect, the present invention provides Epo binding antibodiesthat comprise the heavy chain and light chain CDR1s, CDR2s, and CDR3s asdescribed in Table 1, or combinations thereof. The amino acid sequencesof the VH CDR1s of the antibodies are shown in SEQ ID NOs: 1, 21, 41 or61. The amino acid sequences of the VH CDR2s of the antibodies and areshown in SEQ ID NOs: 2, 22, 42 or 62. The amino acid sequences of the VHCDR3s of the antibodies are shown in SEQ ID NOs: 3, 23, 43, or 63. Theamino acid sequences of the VL CDR1s of the antibodies are shown in SEQID NOs: 4, 24, 44, or 64. The amino acid sequences of the VL CDR2s ofthe antibodies are shown in SEQ ID NOs: 5, 25, 45, or 65. The amino acidsequences of the VL CDR3s of the antibodies are shown in SEQ ID NOs: 6,26, 46, or 66. These CDR regions are delineated using the Kabat system.

Alternatively, as defined using the Chothia system (Al-Lazikani et al.,(1997) JMB 273,927-948) the amino acid sequences of the VH CDR1s of theantibodies are shown in SEQ ID NOs: 7, 27, 47, or 67. The amino acidsequences of the VH CDR2s of the antibodies and are shown in SEQ ID NOs:8, 28, 48, or 68. The amino acid sequences of the VH CDR3s of theantibodies are shown in SEQ ID NOs: 9, 29, 49, or 69. The amino acidsequences of the VL CDR1s of the antibodies are shown in SEQ ID NOs: 10,30, 50, or 70. The amino acid sequences of the VL CDR2s of theantibodies are shown in SEQ ID NOs: 11, 31, 51, or 71. The amino acidsequences of the VL CDR3s of the antibodies are shown in SEQ ID NOs: 12,32, 52, or 72.

Given that each of these antibodies can bind to Epo and thatantigen-binding specificity is provided primarily by the CDR1, 2 and 3regions, the VH CDR1, 2 and 3 sequences and VL CDR1, 2 and 3 sequencescan be “mixed and matched” (i.e., CDRs from different antibodies can bemixed and matched, although each antibody preferably contains a VH CDR1,2 and 3 and a VL CDR1, 2 and 3 to create other Epo binding molecules ofthe invention. Such “mixed and matched” Epo binding antibodies can betested using the binding assays known in the art and those described inthe Examples (e.g., ELISAs, SET, Biacore). When VH CDR sequences aremixed and matched, the CDR1, CDR2 and/or CDR3 sequence from a particularVH sequence should be replaced with a structurally similar CDRsequence(s). Likewise, when VL CDR sequences are mixed and matched, theCDR1, CDR2 and/or CDR3 sequence from a particular VL sequence should bereplaced with a structurally similar CDR sequence(s). It will be readilyapparent to the ordinarily skilled artisan that novel VH and VLsequences can be created by substituting one or more VH and/or VL CDRregion sequences with structurally similar sequences from the CDRsequences shown herein for monoclonal antibodies of the presentinvention. In addition to the foregoing, in one embodiment, the antigenbinding fragments of the antibodies described herein can comprise a VHCDR1, 2, and 3, or a VL CDR 1, 2, and 3, wherein the fragment binds toEpo as a single variable domain.

In certain embodiments of the invention, the antibodies or antigenbinding fragments thereof may have the heavy and light chain sequencesof the Fabs described in Table 1. More specifically, the antibody orantigen binding fragment thereof may have the heavy and light sequenceof Fab NVS1, NVS2, NVS3 or NVS4.

In other embodiments of the invention the antibody or antigen bindingfragment that specifically binds Epo comprises a heavy chain variableregion CDR1, a heavy chain variable region CDR2, a heavy chain variableregion CDR3, a light chain variable region CDR1, a light chain variableregion CDR2, and a light chain variable region CDR3 as defined by Kabatand described in Table 1. In still other embodiments of the inventionthe antibody or antigen binding fragment in that specifically binds Epocomprises a heavy chain variable region CDR1, a heavy chain variableregion CDR2, a heavy chain variable region CDR3, a light chain variableregion CDR1, a light chain variable region CDR2, and a light chainvariable region CDR3 as defined by Chothia and described in Table 1.

In a specific embodiment, the invention includes an antibody thatspecifically binds to Epo comprising a heavy chain variable region CDR1of SEQ ID NO:1; a heavy chain variable region CDR2 of SEQ ID NO: 2; aheavy chain variable region CDR3 of SEQ ID NO: 3; a light chain variableregion CDR1 of SEQ ID NO: 4; a light chain variable region CDR2 of SEQID NO: 5; and a light chain variable region CDR3 of SEQ ID NO: 6. Inanother specific embodiment, the invention includes an antibody thatspecifically binds to Epo comprising a heavy chain variable region CDR1of SEQ ID NO: 21; a heavy chain variable region CDR2 of SEQ ID NO: 22; aheavy chain variable region CDR3 of SEQ ID NO: 23; a light chainvariable region CDR1 of SEQ ID NO: 24; a light chain variable regionCDR2 of SEQ ID NO: 25; and a light chain variable region CDR3 of SEQ IDNO: 26. In another specific embodiment, the invention includes anantibody that specifically binds to Epo comprising a heavy chainvariable region CDR1 of SEQ ID NO: 41; a heavy chain variable regionCDR2 of SEQ ID NO: 42; a heavy chain variable region CDR3 of SEQ ID NO:43; a light chain variable region CDR1 of SEQ ID NO: 44; a light chainvariable region CDR2 of SEQ ID NO: 45; and a light chain variable regionCDR3 of SEQ ID NO: 46. In another specific embodiment, the inventionincludes an antibody that specifically binds to Epo comprising a heavychain variable region CDR1 of SEQ ID NO: 61; a heavy chain variableregion CDR2 of SEQ ID NO: 62; a heavy chain variable region CDR3 of SEQID NO: 63; a light chain variable region CDR1 of SEQ ID NO: 64; a lightchain variable region CDR2 of SEQ ID NO: 65; and a light chain variableregion CDR3 of SEQ ID NO: 66.

In another specific embodiment, the invention includes an antibody thatspecifically binds to Epo comprising a heavy chain variable region CDR1of SEQ ID NO: 7; a heavy chain variable region CDR2 of SEQ ID NO: 8; aheavy chain variable region CDR3 of SEQ ID NO: 9; a light chain variableregion CDR1 of SEQ ID NO: 10; a light chain variable region CDR2 of SEQID NO: 11; and a light chain variable region CDR3 of SEQ ID NO: 12. Inanother specific embodiment, the invention includes an antibody thatspecifically binds to Epo comprising a heavy chain variable region CDR1of SEQ ID NO: 27; a heavy chain variable region CDR2 of SEQ ID NO: 28; aheavy chain variable region CDR3 of SEQ ID NO: 29; a light chainvariable region CDR1 of SEQ ID NO: 30; a light chain variable regionCDR2 of SEQ ID NO: 31; and a light chain variable region CDR3 of SEQ IDNO: 32. In another specific embodiment, the invention includes anantibody that specifically binds to Epo comprising a heavy chainvariable region CDR1 of SEQ ID NO: 47; a heavy chain variable regionCDR2 of SEQ ID NO: 48; a heavy chain variable region CDR3 of SEQ ID NO:49; a light chain variable region CDR1 of SEQ ID NO: 50; a light chainvariable region CDR2 of SEQ ID NO: 51; and a light chain variable regionCDR3 of SEQ ID NO: 52. In another specific embodiment, the inventionincludes an antibody that specifically binds to Epo comprising a heavychain variable region CDR1 of SEQ ID NO: 67; a heavy chain variableregion CDR2 of SEQ ID NO: 68; a heavy chain variable region CDR3 of SEQID NO: 69; a light chain variable region CDR1 of SEQ ID NO: 70; a lightchain variable region CDR2 of SEQ ID NO: 71; and a light chain variableregion CDR3 of SEQ ID NO: 72.

In certain embodiments, the invention includes antibodies or antigenbinding fragments that specifically bind to Epo as described in Table 1.In a preferred embodiment, the antibody, or antigen binding fragment,that binds Epo is Fab NVS1, NVS2, NVS3, or NVS4.

As used herein, a human antibody comprises heavy or light chain variableregions or full length heavy or light chains that are “the product of”or “derived from” a particular germline sequence if the variable regionsor full length chains of the antibody are obtained from a system thatuses human germline immunoglobulin genes. Such systems includeimmunizing a transgenic mouse carrying human immunoglobulin genes withthe antigen of interest or screening a human immunoglobulin gene librarydisplayed on phage with the antigen of interest. A human antibody thatis “the product of” or “derived from” a human germline immunoglobulinsequence can be identified as such by comparing the amino acid sequenceof the human antibody to the amino acid sequences of human germlineimmunoglobulins and selecting the human germline immunoglobulin sequencethat is closest in sequence (i.e., greatest % identity) to the sequenceof the human antibody. A human antibody that is “the product of” or“derived from” a particular human germline immunoglobulin sequence maycontain amino acid differences as compared to the germline sequence, dueto, for example, naturally occurring somatic mutations or intentionalintroduction of site-directed mutations. However, in the VH or VLframework regions, a selected human antibody typically is at least 90%identical in amino acids sequence to an amino acid sequence encoded by ahuman germline immunoglobulin gene and contains amino acid residues thatidentify the human antibody as being human when compared to the germlineimmunoglobulin amino acid sequences of other species (e.g., murinegermline sequences). In certain cases, a human antibody may be at least60%, 70%, 80%, 90%, or at least 95%, or even at least 96%, 97%, 98%, or99% identical in amino acid sequence to the amino acid sequence encodedby the germline immunoglobulin gene. Typically, a recombinant humanantibody will display no more than 10 amino acid differences from theamino acid sequence encoded by the human germline immunoglobulin gene inthe VH or VL framework regions. In certain cases, the human antibody maydisplay no more than 5, or even no more than 4, 3, 2, or 1 amino aciddifference from the amino acid sequence encoded by the germlineimmunoglobulin gene. Examples of human germline immunoglobulin genesinclude, but are not limited to the variable domain germline fragmentsdescribed below, as well as DP47 and DPK9.

Homologous Antibodies

In yet another embodiment, the present invention provides an antibody,or an antigen binding fragment thereof, comprising amino acid sequencesthat are homologous to the sequences described in Table 1, and theantibody binds to an Epo protein (e.g., human, cynomolgus, rat and/ormouse Epo), and retains the desired functional properties of thoseantibodies described in Table 1.

For example, the invention provides an isolated antibody, or afunctional antigen binding fragment thereof, comprising a heavy chainvariable domain and a light chain variable domain, wherein the heavychain variable domain comprises an amino acid sequence that is at least80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% identical to an amino acidsequence selected from the group consisting of SEQ ID NOs: 13, 33, 53,and 73; the light chain variable domain comprises an amino acid sequencethat is at least 80%, 85%, 90%, 95%, 96%, 97%, 98% or 99% identical toan amino acid sequence selected from the group consisting of SEQ ID NOs:14, 34, 54, and 74; and the antibody specifically binds to Epo (e.g.,human, cynomolgus, rat and/or mouse Epo). In certain aspects of theinvention the heavy and light chain sequences further comprise HCDR1,HCDR2, HCDR3, LCDR1, LCDR2, and LCDR3 sequences as defined by Kabat, forexample SEQ ID NOs: 1, 2, 3, 4, 5, and 6, respectively; SEQ ID NOs: 21,22, 23, 24, 25, and 26, respectively; SEQ ID NOs: 41, 42, 43, 44, 45,and 46, respectively; or SEQ ID NOs: 61, 62, 63, 64, 65, and 66,respectively. In certain other aspects of the invention the heavy andlight chain sequences further comprise HCDR1, HCDR2, HCDR3, LCDR1,LCDR2, and LCDR3 sequences as defined by Chothia, for example SEQ IDNOs: 7, 8, 9, 10, 11, and 12, respectively; SEQ ID NOs: 27, 28, 29, 30,31, and 32, respectively; SEQ ID NOs: 47, 48, 49, 50, 51, and 52,respectively; or SEQ ID NOs: 67, 68, 69, 70, 71, and 72, respectively.

In other embodiments, the VH and/or VL amino acid sequences may be 80%,85%, 90%, 95%, 96%, 97%, 98% or 99% identical to the sequences set forthin Table 1. In other embodiments, the VH and/or VL amino acid sequencesmay be identical except for an amino acid substitution in no more than1,2,3,4 or 5 amino acid positions. An antibody having VH and VL regionshaving high (i. e., 80% or greater) identity to the VH and VL regions ofthose described in Table 1 can be obtained by mutagenesis (e.g.,site-directed or PCR-mediated mutagenesis) of nucleic acid moleculesencoding SEQ ID NOs: 13, 33, 53 or 73 and SEQ ID NOs: 14, 34, 54, or 74,respectively, followed by testing of the encoded altered antibody forretained function using the functional assays described herein.

In other embodiments, the full length heavy chain and/or full lengthlight chain amino acid sequences may be 80%, 85%, 90%, 95%, 96%, 97%,98% or 99% identical to the sequences set forth in Table 1. An antibodyhaving a full length heavy chain and full length light chain having high(i.e., 80% or greater) identity to the full length heavy chains of anyof SEQ ID NOs : 15, 35, 55, or 75, and full length light chains of anyof SEQ ID NOs: 16, 36, 56, or 76, can be obtained by mutagenesis (e.g.,site-directed or PCR-mediated mutagenesis) of nucleic acid moleculesencoding such polypeptides, followed by testing of the encoded alteredantibody for retained function using the functional assays describedherein.

In other embodiments, the full length heavy chain and/or full lengthlight chain nucleotide sequences may be 80%, 85%, 90%, 95%, 96%, 97%,98% or 99% identical to the sequences set forth in Table 1.

In other embodiments, the variable regions of heavy chain and/or thevariable regions of light chain nucleotide sequences may be 80%, 85%,90%, 95%, 96%, 97%, 98% or 99% identical to the sequences set forth inTable 1.

As used herein, the percent identity between the two sequences is afunction of the number of identical positions shared by the sequences(i.e., % identity equals number of identical positions/total number ofpositions x 100), taking into account the number of gaps, and the lengthof each gap, which need to be introduced for optimal alignment of thetwo sequences. The comparison of sequences and determination of percentidentity between two sequences can be accomplished using a mathematicalalgorithm, as described in the non-limiting examples below.

Additionally or alternatively, the protein sequences of the presentinvention can further be used as a “query sequence” to perform a searchagainst public databases to, for example, identify related sequences.For example, such searches can be performed using the BLAST program(version 2.0) of Altschul, et al., 1990 J.Mol. Biol. 215:403-10.

Antibodies with Conservative Modifications

In certain embodiments, an antibody of the invention has a heavy chainvariable region comprising CDR1, CDR2, and CDR3 sequences and a lightchain variable region comprising CDR1, CDR2, and CDR3 sequences, whereinone or more of these CDR sequences have specified amino acid sequencesbased on the antibodies described herein or conservative modificationsthereof, and wherein the antibodies retain the desired functionalproperties of the Epo-binding antibodies of the invention. Accordingly,the invention provides an isolated antibody, or an antigen bindingfragment thereof, comprising of a heavy chain variable region comprisingCDR1, CDR2, and CDR3 sequences and a light chain variable regioncomprising CDR1, CDR2, and CDR3 sequences, wherein: the heavy chainvariable region CDR1 amino acid sequences are selected from the groupconsisting of SEQ ID NOs: 1, 21, 41, and 61, and conservativemodifications thereof; the heavy chain variable region CDR2 amino acidsequences are selected from the group consisting of SEQ ID NOs: 2, 22,42 and 62, and conservative modifications thereof; the heavy chainvariable region CDR3 amino acid sequences are selected from the groupconsisting of SEQ ID NOs: 3, 23, 43, and 63, and conservativemodifications thereof; the light chain variable regions CDR1 amino acidsequences are selected from the group consisting of SEQ ID NOs: 4, 24,44 and 64, and conservative modifications thereof; the light chainvariable regions CDR2 amino acid sequences are selected from the groupconsisting of SEQ ID NOs: 5, 25, 45 and 65, and conservativemodifications thereof; the light chain variable regions of CDR3 aminoacid sequences are selected from the group consisting of SEQ ID NOs: 6,26, 46, and 66, and conservative modifications thereof; and the antibodyor antigen binding fragment thereof specifically binds to Epo.

In other embodiments, the antibody of the invention is optimized forexpression in a mammalian cell and has a full length heavy chainsequence and a full length light chain sequence, wherein one or more ofthese sequences have specified amino acid sequences based on theantibodies described herein or conservative modifications thereof, andwherein the antibodies retain the desired functional properties of theEpo binding antibodies of the invention. Accordingly, the inventionprovides an isolated antibody optimized for expression in a mammaliancell consisting of a full length heavy chain and a full length lightchain wherein the full length heavy chain has amino acid sequencesselected from the group of SEQ ID NOs: 15, 35, 55 and 75, andconservative modifications thereof; and the full length light chain hasamino acid sequences selected from the group of SEQ ID NOs: 16, 36, 56,and 76, and conservative modifications thereof; and the antibodyspecifically binds to Epo (e.g., human, cynomolgus, rat and/or mouseEpo).

Antibodies that Bind to the Same Epitope

The present invention provides antibodies that bind to the same epitopeas the Epo binding antibodies described in Table 1. Additionalantibodies can therefore be identified based on their ability to compete(e.g., to competitively inhibit the binding of, in a statisticallysignificant manner) with other antibodies of the invention in Epobinding assays (such as those described in the Examples). The ability ofa test antibody to inhibit the binding of antibodies of the presentinvention to an Epo protein demonstrates that the test antibody cancompete with that antibody for binding to Epo; such an antibody may,according to non-limiting theory, bind to the same or a related (e.g., astructurally similar or spatially proximal) epitope on the Epo proteinas the antibody with which it competes. In a certain embodiment, theantibody that binds to the same epitope on Epo as the antibodies of thepresent invention is a human monoclonal antibody. Such human monoclonalantibodies can be prepared and isolated as described herein. As usedherein, an antibody “competes” for binding when the competing antibodyinhibits Epo binding of an antibody or antigen binding fragment of theinvention by more than 50%, in the presence of an equimolarconcentration of competing antibody.

In other embodiments the antibodies or antigen binding fragments of theinvention bind the Helix D domain of Epo (amino acids 138-162 of the Epoprotein; SEQ ID NO: 88). In other embodiments the antibodies or antigenbinding fragments of the invention bind the Helix A (amino acids 4-26 ofthe Epo protein; SEQ ID NO: 86) and Loop A-B of Epo (amino acids 27-55of the Epo protein; SEQ ID NO: 89).

In other embodiments the antibodies, or antigen binding fragments of theinvention bind to the D Helix domain of Epo (amino acids 138-162 ofHuman Epo; SEQ ID NO: 88). In other embodiments, the isolatedantibodies, or antigen binding fragments bind the Loop A-B domain (aminoacids 27-55 of Human Epo; SEQ ID NO: 89). In other embodiments theisolated antibodies, or antigen binding fragments bind the Loop A-Bdomain (amino acids 27-55 of Human Epo; SEQ ID NO: 89) and Helix A(amino acids 4-26 of Human Epo; SEQ ID NO: 86). In still otherembodiments the isolated antibodies, or antigen binding fragments bindthe D Helix domain of Epo (amino acids 138-162 of Human Epo; SEQ ID NO:88), and the Loop A-B domain (amino acids 27-55 of Human Epo; SEQ ID NO:89). In other embodiments the isolated antibodies, or antigen bindingfragments bind the D Helix domain of Epo (amino acids 138-162 of HumanEpo; SEQ ID NO: 88), the Loop A-B domain (amino acids 27-55 of HumanEpo; SEQ ID NO: 89) and Helix A (amino acids 4-26 of Human Epo; SEQ IDNO: 86).

In other aspects of the invention the isolated antibodies or antigenbinding fragments bind an epitope comprising amino acids at positions,44-50, 52, 53, 147, 150, 151, 154, 155, 159, and 162 of Human Epo (SEQID NO.81). In other aspects of the invention the isolated antibodies orantigen binding fragments bind an epitope comprising amino acids atpositions 9, 13, 44-53, 147, 150, 151, 154, 155, 158, 159, and 162 ofHuman Epo (SEQ ID NO.81). In other aspects of the invention the isolatedantibodies or antigen binding fragments bind an epitope comprising aminoacids at positions 23, 43-50, 52, 53, 131, 143, 147, 150, 151, 154, 155,159, and 162 of Human Epo (SEQ ID NO.81). In particular aspects of theinvention the isolated antibodies or antigen binding fragments bind anepitope comprising amino acids Thr-Lys-Val-Asn-Phe-Tyr-Ala (at positions44-50), Lys-Arg (at positions 52-53), Asn (at position 147), Arg-Gly (atpositions 150-151), Lys-Leu (at positions 154-155), Glu (at position159), and Arg (at position 162) of Human Epo (SEQ ID NO.81). In otherparticular aspects of the invention the isolated antibodies or antigenbinding fragments bind an epitope comprising amino acids Ser (atposition 9), Glu (at position 13), Thr-Lys-Val-Asn-Phe-Tyr-Ala (atpositions 44-50), Lys-Arg (at positions 52-53), Asn (at position 147),Arg-Gly (at positions 150-151), Lys-Leu (at positions 154-155), Gly (atposition 158), Glu (at position 159), and Arg (at position 162) of HumanEpo (SEQ ID NO.81). In still further aspects of the invention theisolated antibodies or antigen binding fragments bind an epitopecomprising amino acids Glu (at positions 23),Asp-Thr-Lys-Val-Asn-Phe-Tyr-Ala (at positions 43-50), Lys-Arg (atpositions 52-53), Arg (at position 131), Arg (at position 143), Asn (atposition 147), Arg-Gly (at positions 150-151), Lys-Leu (at positions154-155), Glu (at position 159), and Arg (at position 162) of Human Epo(SEQ ID NO.81).

The invention also includes a conformational epitope on human Epo, theepitope comprising amino acid residues Thr44, Lys45, Val46, Asn47,Phe48, Tyr49, Ala50, Lys52, Arg53, Asn147, Arg150, Glyl51, Lys154,Leu155, Glu159, and Arg162, wherein an antibody binding to the epitopewill inhibit Epo binding to the Epo receptor. It is also contemplatedthat an antibody binding to the epitope of the invention will furtherinhibit Epo-dependent cell proliferation.

The invention further includes a conformational epitope on human Epo,the epitope comprising amino acid residues Ser9, Glu13, Thr44, Lys45,Val46, Asn47, Phe48, Tyr49, Ala50, Lys52, Arg53, Asn147, Arg150, Gly151,Lys154, Leu155, Gly158, Glu159, and Arg162, wherein an antibody bindingto the epitope will inhibit Epo binding to the Epo receptor. It is alsocontemplated that an antibody binding to the epitope of the inventionwill further inhibit Epo-dependent cell proliferation.

The present invention still further includes a conformational epitope onhuman

Epo, the epitope comprising amino acid residues Glu23, Asp43, Thr44,Lys45, Val46, Asn47, Phe48, Tyr49, Ala50, Lys52, Arg53, Arg131, Arg143,Asn147, Arg150, Gly151, Lys154, Leu155, Glu159, and Arg162, wherein anantibody binding to the epitope will inhibit Epo binding to the Eporeceptor. It is also contemplated that an antibody binding to theepitope of the invention will further inhibit Epo-dependent cellproliferation.

Engineered and Modified Antibodies

An antibody of the invention further can be prepared using an antibodyhaving one or more of the VH and/or VL sequences shown herein asstarting material to engineer a modified antibody, which modifiedantibody may have altered properties from the starting antibody. Anantibody can be engineered by modifying one or more residues within oneor both variable regions (i. e., VH and/or VL), for example within oneor more CDR regions and/or within one or more framework regions.Additionally or alternatively, an antibody can be engineered bymodifying residues within the constant region(s), for example to alterthe effector function(s) of the antibody.

One type of variable region engineering that can be performed is CDRgrafting. Antibodies interact with target antigens predominantly throughamino acid residues that are located in the six heavy and light chaincomplementarity determining regions (CDRs). For this reason, the aminoacid sequences within CDRs are more diverse between individualantibodies than sequences outside of CDRs. Because CDR sequences areresponsible for most antibody-antigen interactions, it is possible toexpress recombinant antibodies that mimic the properties of specificnaturally occurring antibodies by constructing expression vectors thatinclude CDR sequences from the specific naturally occurring antibodygrafted onto framework sequences from a different antibody withdifferent properties (see, e.g., Riechmann, L. et al., 1998 Nature332:323-327; Jones, P. et al., 1986 Nature 321:522-525; Queen, C. etal., 1989 Proc. Natl. Acad., U.S.A. 86:10029-10033; U.S. Pat. No.5,225,539 to Winter, and U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,762and 6,180,370 to Queen et al.)

Accordingly, another embodiment of the invention pertains to an isolatedantibody, or an antigen binding fragment thereof, comprising a heavychain variable region comprising CDR1 sequences having an amino acidsequence selected from the group consisting of SEQ ID NOs: 1, 21, 41,and 61; CDR2 sequences having an amino acid sequence selected from thegroup consisting of SEQ ID NOs: 2, 22, 42, and 62; CDR3 sequences havingan amino acid sequence selected from the group consisting of SEQ ID NOs:3, 23, 43 and 63, respectively; and a light chain variable region havingCDR1 sequences having an amino acid sequence selected from the groupconsisting of SEQ ID NOs: 4, 24, 44 and 64; CDR2 sequences having anamino acid sequence selected from the group consisting of SEQ ID NOs: 5,25, 45, and 65; and CDR3 sequences consisting of an amino acid sequenceselected from the group consisting of SEQ ID NOs: 6, 26, 46, and 66,respectively. Thus, such antibodies contain the VH and VL CDR sequencesof monoclonal antibodies, yet may contain different framework sequencesfrom these antibodies.

Alternatively, another embodiment of the invention pertains to anisolated antibody, or an antigen binding fragment thereof, comprising aheavy chain variable region comprising CDR1 sequences having an aminoacid sequence selected from the group consisting of SEQ ID NOs: 7, 27,47, and 67; CDR2 sequences having an amino acid sequence selected fromthe group consisting of SEQ ID NOs: 8, 28, 48, and 68; CDR3 sequenceshaving an amino acid sequence selected from the group consisting of SEQID NOs: 9, 29, 49, and 69, respectively; and a light chain variableregion having CDR1 sequences having an amino acid sequence selected fromthe group consisting of SEQ ID NOs: 10, 30, 50, and 70; CDR2 sequenceshaving an amino acid sequence selected from the group consisting of SEQID NOs: 11, 31, 51, and 71; and CDR3 sequences consisting of an aminoacid sequence selected from the group consisting of SEQ ID NOs: 12, 32,52, and 72, respectively. Thus, such antibodies contain the VH and VLCDR sequences of monoclonal antibodies, yet may contain differentframework sequences from these antibodies.

Such framework sequences can be obtained from public DNA databases orpublished references that include germline antibody gene sequences. Forexample, germline DNA sequences for human heavy and light chain variableregion genes can be found in the “VBase” human germline sequencedatabase (available on the world wide web at mrc- cpe.cam.ac.uk/vbase),as well as in Kabat, E. A., et al., 1991 Sequences of Proteins ofImmunological Interest, Fifth Edition, U.S. Department of Health andHuman Services, NIH Publication No. 91-3242; Tomlinson, I. M., et al.,1992 J. Mol. Biol. 227:776-798; and Cox, J. P. L. et al., 1994 Eur. JImmunol. 24:827-836; the contents of each of which are expresslyincorporated herein by reference.

An example of framework sequences for use in the antibodies of theinvention are those that are structurally similar to the frameworksequences used by selected antibodies of the invention, e.g., consensussequences and/or framework sequences used by monoclonal antibodies ofthe invention. The VH CDR1, 2 and 3 sequences, and the VL CDR1, 2 and 3sequences, can be grafted onto framework regions that have the identicalsequence as that found in the germline immunoglobulin gene from whichthe framework sequence derive, or the CDR sequences can be grafted ontoframework regions that contain one or more mutations as compared to thegermline sequences. For example, it has been found that in certaininstances it is beneficial to mutate residues within the frameworkregions to maintain or enhance the antigen binding ability of theantibody (see e.g., U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,762 and6,180,370 to Queen et al). Frameworks that can be utilized as scaffoldson which to build the antibodies and antigen binding fragments describedherein include, but are not limited to VH1A, VH1B, VH3, Vk1, Vl2, andVk2. Additional frameworks are known in the art and may be found, forexample, in the vBase data base on the world wide web atvbase.mrc-cpe.cam.ac.uk/index.php?&MMN_position=1:1.

Accordingly, an embodiment of the invention relates to isolated Epobinding antibodies, or antigen binding fragments thereof, comprising aheavy chain variable region comprising an amino acid sequence selectedfrom the group consisting of SEQ ID NOs: 13, 33, 53, and 73, or an aminoacid sequence having one, two, three, four or five amino acidsubstitutions, deletions or additions in the framework region of suchsequences, and further comprising a light chain variable region havingan amino acid sequence selected from the group consisting of SEQ ID NOs:14, 34, 54, and 74, or an amino acid sequence having one, two, three,four or five amino acid substitutions, deletions or additions in theframework region of such sequences.

Another type of variable region modification is to mutate amino acidresidues within the VH and/or VL CDR1, CDR2 and/or CDR3 regions tothereby improve one or more binding properties (e.g., affinity) of theantibody of interest, known as “affinity maturation.” Site-directedmutagenesis or PCR-mediated mutagenesis can be performed to introducethe mutation(s) and the effect on antibody binding, or other functionalproperty of interest, can be evaluated in in vitro or in vivo assays asdescribed herein and provided in the Examples. Conservativemodifications (as discussed above) can be introduced. The mutations maybe amino acid substitutions, additions or deletions. Moreover, typicallyno more than one, two, three, four or five residues within a CDR regionare altered.

Accordingly, in another embodiment, the invention provides isolatedEpo-binding antibodies, or antigen binding fragments thereof, consistingof a heavy chain variable region having a VH CDR1 region consisting ofan amino acid sequence selected from the group having SEQ ID NOs: 1, 21,41, and 61 or an amino acid sequence having one, two, three, four orfive amino acid substitutions, deletions or additions as compared to SEQID NOs: 1, 21, 41, or 61; a VH CDR2 region having an amino acid sequenceselected from the group consisting of SEQ ID NOs: 2, 22, 42, and 62 oran amino acid sequence having one, two, three, four or five amino acidsubstitutions, deletions or additions as compared to SEQ ID NOs: 2, 22,42, or 62; a VH CDR3 region having an amino acid sequence selected fromthe group consisting of SEQ ID NOs: 3, 23, 43, and 63, or an amino acidsequence having one, two, three, four or five amino acid substitutions,deletions or additions as compared to SEQ ID NOs: 3, 23, 43, or 63; a VLCDR1 region having an amino acid sequence selected from the groupconsisting of SEQ ID NOs: 4, 24, 44, and 64, or an amino acid sequencehaving one, two, three, four or five amino acid substitutions, deletionsor additions as compared to SEQ ID NOs: 4, 24, 44, or 64; a VL CDR2region having an amino acid sequence selected from the group consistingof SEQ ID NOs: 5, 25, 45, and 65, or an amino acid sequence having one,two, three, four or five amino acid substitutions, deletions oradditions as compared to SEQ ID NOs: 5, 25, 45, or 65; and a VL CDR3region having an amino acid sequence selected from the group consistingof SEQ ID NOs: 6, 26, 46, and 66, or an amino acid sequence having one,two, three, four or five amino acid substitutions, deletions oradditions as compared to SEQ ID NOs: 6, 26, 46, or 66.

Accordingly, in another embodiment, the invention provides isolatedEpo-binding antibodies, or antigen binding fragments thereof, consistingof a heavy chain variable region having a VH CDR1 region consisting ofan amino acid sequence selected from the group having SEQ ID NOs: 7, 27,47, and 67 or an amino acid sequence having one, two, three, four orfive amino acid substitutions, deletions or additions as compared to SEQID NOs:7, 27, 47, or 67; a VH CDR2 region having an amino acid sequenceselected from the group consisting of SEQ ID NOs: 8, 28, 48, and 68 oran amino acid sequence having one, two, three, four or five amino acidsubstitutions, deletions or additions as compared to SEQ ID NOs: 8, 28,48, or 68; a VH CDR3 region having an amino acid sequence selected fromthe group consisting of SEQ ID NOs: 9, 29, 49, and 69, or an amino acidsequence having one, two, three, four or five amino acid substitutions,deletions or additions as compared to SEQ ID NOs: 9, 29, 49, or 69; a VLCDR1 region having an amino acid sequence selected from the groupconsisting of SEQ ID NOs: 10, 30, 50, and 70, or an amino acid sequencehaving one, two, three, four or five amino acid substitutions, deletionsor additions as compared to SEQ ID NOs: 10, 30 50, or 70; a VL CDR2region having an amino acid sequence selected from the group consistingof SEQ ID NOs: 11, 31, 51, and 71, or an amino acid sequence having one,two, three, four or five amino acid substitutions, deletions oradditions as compared to SEQ ID NOs: 11, 31, 51, or 71; and a VL CDR3region having an amino acid sequence selected from the group consistingof SEQ ID NOs: 12, 32, 52, and 72, or an amino acid sequence having one,two, three, four or five amino acid substitutions, deletions oradditions as compared to SEQ ID NOs: 12, 32, 52, or 72.

Grafting Antigen-Binding Domains into Alternative Frameworks orScaffolds

A wide variety of antibody/immunoglobulin frameworks or scaffolds can beemployed so long as the resulting polypeptide includes at least onebinding region which specifically binds to Epo. Such frameworks orscaffolds include the 5 main idiotypes of human immunoglobulins, orfragments thereof, and include immunoglobulins of other animal species,preferably having humanized aspects. Single heavy-chain antibodies suchas those identified in camelids are of particular interest in thisregard. Novel frameworks, scaffolds and fragments continue to bediscovered and developed by those skilled in the art.

In one aspect, the invention pertains to generating non-immunoglobulinbased antibodies using non-immunoglobulin scaffolds onto which CDRs ofthe invention can be grafted. Known or future non-immunoglobulinframeworks and scaffolds may be employed, as long as they comprise abinding region specific for the target Epo protein. Knownnon-immunoglobulin frameworks or scaffolds include, but are not limitedto, fibronectin (Compound Therapeutics, Inc., Waltham, Mass.), ankyrin(Molecular Partners AG, Zurich, Switzerland), domain antibodies(Domantis, Ltd., Cambridge, Mass., and Ablynx nv, Zwijnaarde, Belgium),lipocalin (Pieris Proteolab AG, Freising, Germany), small modularimmuno-pharmaceuticals (Trubion Pharmaceuticals Inc., Seattle, Wash.),maxybodies (Avidia, Inc., Mountain View, Calif.), Protein A (AffibodyAG, Sweden), and affilin (gamma-crystallin or ubiquitin) (Scil ProteinsGmbH, Halle, Germany).

The fibronectin scaffolds are based on fibronectin type III domain(e.g., the tenth module of the fibronectin type III (10 Fn3 domain)).The fibronectin type III domain has 7 or 8 beta strands which aredistributed between two beta sheets, which themselves pack against eachother to form the core of the protein, and further containing loops(analogous to CDRs) which connect the beta strands to each other and aresolvent exposed. There are at least three such loops at each edge of thebeta sheet sandwich, where the edge is the boundary of the proteinperpendicular to the direction of the beta strands (see U.S. Pat. No.6,818,418). These fibronectin-based scaffolds are not an immunoglobulin,although the overall fold is closely related to that of the smallestfunctional antibody fragment, the variable region of the heavy chain,which comprises the entire antigen recognition unit in camel and llamaIgG. Because of this structure, the non-immunoglobulin antibody mimicsantigen binding properties that are similar in nature and affinity tothose of antibodies. These scaffolds can be used in a loop randomizationand shuffling strategy in vitro that is similar to the process ofaffinity maturation of antibodies in vivo. These fibronectin-basedmolecules can be used as scaffolds where the loop regions of themolecule can be replaced with CDRs of the invention using standardcloning techniques.

The ankyrin technology is based on using proteins with ankyrin derivedrepeat modules as scaffolds for bearing variable regions which can beused for binding to different targets. The ankyrin repeat module is a 33amino acid polypeptide consisting of two anti-parallel α-helices and aβ-turn. Binding of the variable regions is mostly optimized by usingribosome display.

Avimers are derived from natural A-domain containing protein such asLRP-1. These domains are used by nature for protein-protein interactionsand in human over 250 proteins are structurally based on A-domains.Avimers consist of a number of different “A-domain” monomers (2-10)linked via amino acid linkers. Avimers can be created that can bind tothe target antigen using the methodology described in, for example, U.S.Patent Application Publication Nos. 20040175756; 20050053973;20050048512; and 20060008844.

Affibody affinity ligands are small, simple proteins composed of athree-helix bundle based on the scaffold of one of the IgG-bindingdomains of Protein A. Protein A is a surface protein from the bacteriumStaphylococcus aureus. This scaffold domain consists of 58 amino acids,13 of which are randomized to generate affibody libraries with a largenumber of ligand variants (See e.g., U.S. Pat. No. 5,831,012). Affibodymolecules mimic antibodies, they have a molecular weight of 6 kDa,compared to the molecular weight of antibodies, which is 150 kDa. Inspite of its small size, the binding site of affibody molecules issimilar to that of an antibody.

Anticalins are products developed by the company Pieris ProteoLab AG.They are derived from lipocalins, a widespread group of small and robustproteins that are usually involved in the physiological transport orstorage of chemically sensitive or insoluble compounds. Several naturallipocalins occur in human tissues or body liquids. The proteinarchitecture is reminiscent of immunoglobulins, with hypervariable loopson top of a rigid framework. However, in contrast with antibodies ortheir recombinant fragments, lipocalins are composed of a singlepolypeptide chain with 160 to 180 amino acid residues, being justmarginally bigger than a single immunoglobulin domain. The set of fourloops, which makes up the binding pocket, shows pronounced structuralplasticity and tolerates a variety of side chains. The binding site canthus be reshaped in a proprietary process in order to recognizeprescribed target molecules of different shape with high affinity andspecificity. One protein of lipocalin family, the bilin-binding protein(BBP) of Pieris brassicae has been used to develop anticalins bymutagenizing the set of four loops. One example of a patent applicationdescribing anticalins is in PCT Publication No. WO 1999/16873.

Affilin molecules are small non-immunoglobulin proteins which aredesigned for specific affinities towards proteins and small molecules.New affilin molecules can be very quickly selected from two libraries,each of which is based on a different human derived scaffold protein.Affilin molecules do not show any structural homology to immunoglobulinproteins. Currently, two affilin scaffolds are employed, one of which isgamma crystalline, a human structural eye lens protein and the other is“ubiquitin” superfamily proteins. Both human scaffolds are very small,show high temperature stability and are almost resistant to pH changesand denaturing agents. This high stability is mainly due to the expandedbeta sheet structure of the proteins. Examples of gamma crystallinederived proteins are described in WO 2001/04144 and examples of“ubiquitin-like” proteins are described in WO 2004/106368.

Protein epitope mimetics (PEM) are medium-sized, cyclic, peptide-likemolecules (MW 1-2 kDa) mimicking beta-hairpin secondary structures ofproteins, the major secondary structure involved in protein-proteininteractions.

The present invention provides fully human antibodies that specificallybind to an Epo protein. Compared to the chimeric or humanizedantibodies, the human Epo-binding antibodies of the invention havefurther reduced antigenicity when administered to human subjects.

Camelid Antibodies

Antibody proteins obtained from members of the camel and dromedary(Camelus bactrianus and Camelus dromaderius) family including new worldmembers such as llama species (Lama pacos, Lama glama and Lama vicugna)have been characterized with respect to size, structural complexity andantigenicity for human subjects. Certain IgG antibodies from this familyof mammals as found in nature lack light chains, and are thusstructurally distinct from the typical four chain quaternary structurehaving two heavy and two light chains, for antibodies from otheranimals. See PCT/EP93/02214 (WO 94/04678 published 3 Mar. 1994).

A region of the camelid antibody which is the small single variabledomain identified as VHH can be obtained by genetic engineering to yielda small protein having high affinity for a target, resulting in a lowmolecular weight antibody-derived protein known as a “camelid nanobody”.See U.S. Pat. No. 5,759,808 issued Jun. 2, 1998; see also Stijlemans, B.et al., 2004 J Biol Chem 279: 1256-1261; Dumoulin, M. et al., 2003Nature 424: 783-788; Pleschberger, M. et al. 2003 Bioconjugate Chem 14:440-448; Cortez-Retamozo, V. et al. 2002 Int J Cancer 89: 456-62; andLauwereys, M. et al. 1998 EMBO J 17: 3512-3520. Engineered libraries ofcamelid antibodies and antibody fragments are commercially available,for example, from Ablynx, Ghent, Belgium. As with other antibodies ofnon-human origin, an amino acid sequence of a camelid antibody can bealtered recombinantly to obtain a sequence that more closely resembles ahuman sequence, i.e., the nanobody can be “humanized”. Thus the naturallow antigenicity of camelid antibodies to humans can be further reduced.

The camelid nanobody has a molecular weight approximately one-tenth thatof a human IgG molecule, and the protein has a physical diameter of onlya few nanometers. One consequence of the small size is the ability ofcamelid nanobodies to bind to antigenic sites that are functionallyinvisible to larger antibody proteins, i.e., camelid nanobodies areuseful as reagents detect antigens that are otherwise cryptic usingclassical immunological techniques, and as possible therapeutic agents.Thus yet another consequence of small size is that a camelid nanobodycan inhibit as a result of binding to a specific site in a groove ornarrow cleft of a target protein, and hence can serve in a capacity thatmore closely resembles the function of a classical low molecular weightdrug than that of a classical antibody.

The low molecular weight and compact size further result in camelidnanobodies being extremely thermostable, stable to extreme pH and toproteolytic digestion, and poorly antigenic. Another consequence is thatcamelid nanobodies readily move from the circulatory system intotissues, and even cross the blood-brain barrier and can treat disordersthat affect nervous tissue. Nanobodies can further facilitated drugtransport across the blood brain barrier. See U.S. patent application20040161738 published Aug. 19, 2004. These features combined with thelow antigenicity to humans indicate great therapeutic potential.Further, these molecules can be fully expressed in prokaryotic cellssuch as E. coli and are expressed as fusion proteins with bacteriophageand are functional.

Accordingly, a feature of the present invention is a camelid antibody ornanobody having high affinity for Epo. In certain embodiments herein,the camelid antibody or nanobody is naturally produced in the camelidanimal, i.e., is produced by the camelid following immunization with Epoor a peptide fragment thereof, using techniques described herein forother antibodies. Alternatively, the Epo-binding camelid nanobody isengineered, i.e., produced by selection for example from a library ofphage displaying appropriately mutagenized camelid nanobody proteinsusing panning procedures with Epo as a target as described in theexamples herein. Engineered nanobodies can further be customized bygenetic engineering to have a half-life in a recipient subject of from45 minutes to two weeks. In a specific embodiment, the camelid antibodyor nanobody is obtained by grafting the CDRs sequences of the heavy orlight chain of the human antibodies of the invention into nanobody orsingle domain antibody framework sequences, as described for example inWO 1994/004678.

Bispecific Molecules and Multivalent Antibodies

In another aspect, the present invention features bispecific ormultispecific molecules comprising an Epo-binding antibody, or afragment thereof, of the invention. An antibody of the invention, orantigen-binding regions thereof, can be derivatized or linked to anotherfunctional molecule, e.g., another peptide or protein (e.g., anotherantibody or ligand for a receptor) to generate a bispecific moleculethat binds to at least two different binding sites or target molecules.The antibody of the invention may in fact be derivatized or linked tomore than one other functional molecule to generate multi-specificmolecules that bind to more than two different binding sites and/ortarget molecules; such multi-specific molecules are also intended to beencompassed by the term “bispecific molecule” as used herein. To createa bispecific molecule of the invention, an antibody of the invention canbe functionally linked (e.g., by chemical coupling, genetic fusion,noncovalent association or otherwise) to one or more other bindingmolecules, such as another antibody, antibody fragment, peptide orbinding mimetic, such that a bispecific molecule results.

Accordingly, the present invention includes bispecific moleculescomprising at least one first binding specificity for Epo and a secondbinding specificity for a second target epitope. For example, the secondtarget epitope is another epitope of Epo different from the first targetepitope.

Additionally, for the invention in which the bispecific molecule ismulti-specific, the molecule can further include a third bindingspecificity, in addition to the first and second target epitope.

In one embodiment, the bispecific molecules of the invention comprise asa binding specificity at least one antibody, or an antibody fragmentthereof, including, e.g., a Fab, Fab′, F(ab′)2, Fv, or a single chainFv. The antibody may also be a light chain or heavy chain dimer, or anyminimal fragment thereof such as a Fv or a single chain construct asdescribed in Ladner et al. U.S. Pat. No. 4,946,778.

Diabodies are bivalent, bispecific molecules in which VH and VL domainsare expressed on a single polypeptide chain, connected by a linker thatis too short to allow for pairing between the two domains on the samechain. The VH and VL domains pair with complementary domains of anotherchain, thereby creating two antigen binding sites (see e.g., Holliger etal., 1993 Proc. Natl. Acad. Sci. USA 90:6444-6448; Poljak et al., 1994Structure 2:1121-1123). Diabodies can be produced by expressing twopolypeptide chains with either the structure VHA-VLB and VHB-VLA (VH-VLconfiguration), or VLA-VHB and VLB-VHA (VL-VH configuration) within thesame cell. Most of them can be expressed in soluble form in bacteria.Single chain diabodies (scDb) are produced by connecting the twodiabody-forming polypeptide chains with linker of approximately 15 aminoacid residues (see Holliger and Winter, 1997 Cancer Immunol.Immunother., 45(3-4):128-30; Wu et al., 1996 Immunotechnology,2(1):21-36). scDb can be expressed in bacteria in soluble, activemonomeric form (see Holliger and Winter, 1997 Cancer Immunol.Immunother., 45(34): 128-30; Wu et al., 1996 Immunotechnology,2(1):21-36; Pluckthun and Pack, 1997 Immunotechnology, 3(2): 83-105;Ridgway et al., 1996 Protein Eng., 9(7):617-21). A diabody can be fusedto Fc to generate a “di-diabody” (see Lu et al., 2004 J. Biol. Chem.,279(4):2856-65).

Other antibodies which can be employed in the bispecific molecules ofthe invention are murine, chimeric and humanized monoclonal antibodies.

Bispecific molecules can be prepared by conjugating the constituentbinding specificities, using methods known in the art. For example, eachbinding specificity of the bispecific molecule can be generatedseparately and then conjugated to one another. When the bindingspecificities are proteins or peptides, a variety of coupling orcross-linking agents can be used for covalent conjugation. Examples ofcross-linking agents include protein A, carbodiimide,N-succinimidyl-S-acetyl-thioacetate (SATA),5,5′-dithiobis(2-nitrobenzoic acid) (DTNB), o-phenylenedimaleimide(oPDM), N-succinimidyl-3-(2-pyridyldithio)propionate (SPDP), andsulfosuccinimidyl 4-(N-maleimidomethyl) cyclohaxane-1-carboxylate(sulfo-SMCC) (see e.g., Karpovsky et al., 1984 J. Exp. Med. 160:1686;Liu, MA et al., 1985 Proc. Natl. Acad. Sci. USA 82:8648). Other methodsinclude those described in Paulus, 1985 Behring Ins. Mitt. No.78,118-132; Brennan et al., 1985 Science 229:81-83), and Glennie et al.,1987 J. Immunol. 139: 2367-2375). Conjugating agents are SATA andsulfo-SMCC, both available from Pierce Chemical Co. (Rockford, Ill.).

When the binding specificities are antibodies, they can be conjugated bysulfhydryl bonding of the C-terminus hinge regions of the two heavychains. In a particularly embodiment, the hinge region is modified tocontain an odd number of sulfhydryl residues, for example one, prior toconjugation.

Alternatively, both binding specificities can be encoded in the samevector and expressed and assembled in the same host cell. This method isparticularly useful where the bispecific molecule is a mAb x mAb, mAb xFab, Fab x F(ab′)2 or ligand x Fab fusion protein. A bispecific moleculeof the invention can be a single chain molecule comprising one singlechain antibody and a binding determinant, or a single chain bispecificmolecule comprising two binding determinants. Bispecific molecules maycomprise at least two single chain molecules. Methods for preparingbispecific molecules are described for example in U.S. Pat. Nos.5,260,203; 5,455,030; 4,881,175; 5,132,405; 5,091,513; 5,476,786;5,013,653; 5,258,498; and 5,482,858.

Binding of the bispecific molecules to their specific targets can beconfirmed by, for example, enzyme-linked immunosorbent assay (ELISA),radioimmunoassay (REA), FACS analysis, bioassay (e.g., growthinhibition), or Western Blot assay. Each of these assays generallydetects the presence of protein-antibody complexes of particularinterest by employing a labeled reagent (e.g., an antibody) specific forthe complex of interest.

In another aspect, the present invention provides multivalent compoundscomprising at least two identical or different antigen-binding portionsof the antibodies of the invention binding to Epo. The antigen-bindingportions can be linked together via protein fusion or covalent ornoncovalent linkage. Alternatively, methods of linkage have beendescribed for the bispecific molecules. Tetravalent compounds can beobtained for example by cross-linking antibodies of the antibodies ofthe invention with an antibody that binds to the constant regions of theantibodies of the invention, for example the Fc or hinge region.

Trimerizing domain are described for example in Borean patent EP 1 012280B1. Pentamerizing modules are described for example in WO1998/018943.

Antibodies with Extended Half Life

The present invention provides for antibodies that specifically bind toEpo protein which have an extended half-life in vivo.

Many factors may affect a protein's half-life in vivo, for example,kidney filtration, metabolism in the liver, degradation by proteolyticenzymes (proteases), and immunogenic responses (e.g., proteinneutralization by antibodies and uptake by macrophages and dendriticcells). A variety of strategies can be used to extend the half-life ofthe antibodies of the present invention. For example, by chemicallinkage to polyethyleneglycol (PEG), reCODE PEG, antibody scaffold,polysialic acid (PSA), hydroxyethyl starch (HES), albumin-bindingligands, and carbohydrate shields; by genetic fusion to proteins bindingto serum proteins, such as albumin, IgG, FcRn, and transferring; bycoupling (genetically or chemically) to other binding moieties that bindto serum proteins, such as nanobodies, Fabs, DARPins, avimers,affibodies, and anticalins; by genetic fusion to rPEG, albumin, domainof albumin, albumin-binding proteins, and Fc; or by incorporation intonanocarriers, slow release formulations, or medical devices.

To prolong the serum circulation of antibodies in vivo, inert polymermolecules such as high molecular weight polyethylene glycol (PEG) can beattached to the antibodies or a fragment thereof with or without amultifunctional linker either through site-specific conjugation of thePEG to the N- or C-terminus of the antibodies or via epsilon-aminogroups present on lysine residues. To pegylate an antibody, theantibody, or fragment thereof, typically is reacted with PEG, such as areactive ester or aldehyde derivative of PEG, under conditions in whichone or more PEG groups become attached to the antibody or antibodyfragment. The pegylation can be carried out by an acylation reaction oran alkylation reaction with a reactive PEG molecule (or an analogousreactive water-soluble polymer). As used herein, the terms “polyethyleneglycol” and “PEG” are intended to encompass any of the forms of PEG thathave been used to derivatize other proteins, such as mono (C1-C10)alkoxy- or aryloxy-polyethylene glycol or polyethylene glycol-maleimide.In certain embodiments, the antibody to be pegylated is an aglycosylatedantibody. Linear or branched polymer derivatization that results inminimal loss of biological activity will be used. The degree ofconjugation can be closely monitored by SDS-PAGE and mass spectrometryto ensure proper conjugation of PEG molecules to the antibodies.Unreacted PEG can be separated from antibody-PEG conjugates bysize-exclusion or by ion-exchange chromatography. PEG-derivatizedantibodies can be tested for binding activity as well as for in vivoefficacy using methods well-known to those of skill in the art, forexample, by immunoassays described herein. Methods for pegylatingproteins are known in the art and can be applied to the antibodies ofthe invention. See for example, EP 0 154 316 by Nishimura et al. and EP0 401 384 by Ishikawa et al.

Other modified pegylation technologies include reconstituting chemicallyorthogonal directed engineering technology (ReCODE PEG), whichincorporates chemically specified side chains into biosynthetic proteinsvia a reconstituted system that includes tRNA synthetase and tRNA. Thistechnology enables incorporation of more than 30 new amino acids intobiosynthetic proteins in E. coli, yeast, and mammalian cells. The tRNAincorporates a nonnative amino acid any place an amber codon ispositioned, converting the amber from a stop codon to one that signalsincorporation of the chemically specified amino acid.

Recombinant pegylation technology (rPEG) can also be used for serumhalf-life extension. This technology involves genetically fusing a300-600 amino acid unstructured protein tail to an existingpharmaceutical protein. Because the apparent molecular weight of such anunstructured protein chain is about 15-fold larger than its actualmolecular weight, the serum half-life of the protein is greatlyincreased. In contrast to traditional PEGylation, which requireschemical conjugation and repurification, the manufacturing process isgreatly simplified and the product is homogeneous.

Polysialytion is another technology, which uses the natural polymerpolysialic acid (PSA) to prolong the active life and improve thestability of therapeutic peptides and proteins. PSA is a polymer ofsialic acid (a sugar). When used for protein and therapeutic peptidedrug delivery, polysialic acid provides a protective microenvironment onconjugation. This increases the active life of the therapeutic proteinin the circulation and prevents it from being recognized by the immunesystem. The PSA polymer is naturally found in the human body. It wasadopted by certain bacteria which evolved over millions of years to coattheir walls with it. These naturally polysialylated bacteria were thenable, by virtue of molecular mimicry, to foil the body's defense system.PSA, nature's ultimate stealth technology, can be easily produced fromsuch bacteria in large quantities and with predetermined physicalcharacteristics. Bacterial PSA is completely non-immunogenic, even whencoupled to proteins, as it is chemically identical to PSA in the humanbody.

Another technology includes the use of hydroxyethyl starch (“HES”)derivatives linked to antibodies. HES is a modified natural polymerderived from waxy maize starch and can be metabolized by the body'senzymes. HES solutions are usually administered to substitute deficientblood volume and to improve the rheological properties of the blood.Hesylation of an antibody enables the prolongation of the circulationhalf-life by increasing the stability of the molecule, as well as byreducing renal clearance, resulting in an increased biological activity.By varying different parameters, such as the molecular weight of HES, awide range of HES antibody conjugates can be customized.

Antibodies having an increased half-life in vivo can also be generatedintroducing one or more amino acid modifications (i.e., substitutions,insertions or deletions) into an IgG constant domain, or FcRn bindingfragment thereof (preferably a Fc or hinge Fc domain fragment). See,e.g., International Publication No. WO 98/23289; InternationalPublication No. WO 97/34631; and U.S. Pat. No. 6,277,375.

Further, antibodies can be conjugated to albumin (e.g., human serumalbumin; HSA) in order to make the antibody or antibody fragment morestable in vivo or have a longer half-life in vivo. The techniques arewell-known in the art, see, e.g., International Publication Nos. WO93/15199, WO 93/15200, and WO 01/77137; and European Patent No. EPO413622. In addition, in the context of a bispecific antibody asdescribed above, the specificities of the antibody can be designed suchthat one binding domain of the antibody binds to Epo while a secondbinding domain of the antibody binds to serum albumin, preferably HSA.

The strategies for increasing half-life are especially useful innanobodies, fibronectin-based binders, and other antibodies or proteinsfor which increased in vivo half-life is desired.

Antibody Conjugates

The present invention provides antibodies or fragments thereof thatspecifically bind to an Epo protein recombinantly fused or chemicallyconjugated (including both covalent and non-covalent conjugations) to aheterologous protein or polypeptide (or fragment thereof, preferably toa polypeptide of at least 10, at least 20, at least 30, at least 40, atleast 50, at least 60, at least 70, at least 80, at least 90 or at least100 amino acids) to generate fusion proteins. In particular, theinvention provides fusion proteins comprising an antigen-bindingfragment of an antibody described herein (e.g., a Fab fragment, Fdfragment, Fv fragment, F(ab)2 fragment, a VH domain, a VH CDR, a VLdomain or a VL CDR) and a heterologous protein, polypeptide, or peptide.Methods for fusing or conjugating proteins, polypeptides, or peptides toan antibody or an antibody fragment are known in the art. See, e.g.,U.S. Pat. Nos. 5,336,603, 5,622,929, 5,359,046, 5,349,053, 5,447,851,and 5,112,946; European Patent Nos. EP 0307434 and EP 0367166;International Publication Nos. WO 96/04388 and WO 91/06570; Ashkenazi etal., 1991, Proc. Natl. Acad. Sci. USA 88: 10535-10539; Zheng et al.,1995, J. Immunol. 154:5590-5600; and Vil et al., 1992, Proc. Natl. Acad.Sci. USA 89:11337-11341.

Additional fusion proteins may be generated through the techniques ofgene-shuffling, motif-shuffling, exon-shuffling, and/or codon-shuffling(collectively referred to as “DNA shuffling”). DNA shuffling may beemployed to alter the activities of antibodies of the invention orfragments thereof (e.g., antibodies or fragments thereof with higheraffinities and lower dissociation rates). See, generally, U.S. Pat. Nos.5,605,793, 5,811,238, 5,830,721, 5,834,252, and 5,837,458; Patten etal., 1997, Curr. Opinion Biotechnol. 8:724-33; Harayama, 1998, TrendsBiotechnol. 16(2):76-82; Hansson, et al., 1999, J. Mol. Biol.287:265-76; and Lorenzo and Blasco, 1998, Biotechniques 24(2):308-313(each of these patents and publications are hereby incorporated byreference in its entirety). Antibodies or fragments thereof, or theencoded antibodies or fragments thereof, may be altered by beingsubjected to random mutagenesis by error-prone PCR, random nucleotideinsertion or other methods prior to recombination. A polynucleotideencoding an antibody or fragment thereof that specifically binds to anEpo protein may be recombined with one or more components, motifs,sections, parts, domains, fragments, etc. of one or more heterologousmolecules.

Moreover, the antibodies or fragments thereof can be fused to markersequences, such as a peptide to facilitate purification. In preferredembodiments, the marker amino acid sequence is a hexa-histidine peptide,such as the tag provided in a pQE vector (QIAGEN, Inc., 9259 EtonAvenue, Chatsworth, Calif., 91311), among others, many of which arecommercially available. As described in Gentz et al., 1989, Proc. Natl.Acad. Sci. USA 86:821-824, for instance, hexa-histidine provides forconvenient purification of the fusion protein. Other peptide tags usefulfor purification include, but are not limited to, the hemagglutinin(“HA”) tag, which corresponds to an epitope derived from the influenzahemagglutinin protein (Wilson et al., 1984, Cell 37:767), and the “flag”tag.

In other embodiments, antibodies of the present invention or fragmentsthereof conjugated to a diagnostic or detectable agent. Such antibodiescan be useful for monitoring or prognosing the onset, development,progression and/or severity of a disease or disorder as part of aclinical testing procedure, such as determining the efficacy of aparticular therapy. Such diagnosis and detection can be accomplished bycoupling the antibody to detectable substances including, but notlimited to, various enzymes, such as, but not limited to, horseradishperoxidase, alkaline phosphatase, beta-galactosidase, oracetylcholinesterase; prosthetic groups, such as, but not limited to,streptavidin/biotin and avidin/biotin; fluorescent materials, such as,but not limited to, umbelliferone, fluorescein, fluoresceinisothiocynate, rhodamine, dichlorotriazinylamine fluorescein, dansylchloride or phycoerythrin; luminescent materials, such as, but notlimited to, luminol; bioluminescent materials, such as but not limitedto, luciferase, luciferin, and aequorin; radioactive materials, such as,but not limited to, iodine (131I, 125I, 123I, and 121I,), carbon (14C),sulfur (35S), tritium (3H), indium (115In, 113In, 112In, and 111In,),technetium (99Tc), thallium (201Ti), gallium (68Ga, 67Ga), palladium(103Pd), molybdenum (99Mo), xenon (133Xe), fluorine (18F), 153Sm, 177Lu,159Gd, 149Pm, 140La, 175Yb, 166Ho, 90Y, 47Sc, 186Re, 188Re,142 Pr,105Rh, 97Ru, 68Ge, 57Co, 65Zn, 85Sr, 32P, 153Gd, 169Yb, 51Cr, 54Mn,75Se, 113Sn, and 117Tin; and positron emitting metals using variouspositron emission tomographies, and non-radioactive paramagnetic metalions.

The present invention further encompasses uses of antibodies orfragments thereof conjugated to a therapeutic moiety. An antibody orfragment thereof may be conjugated to a therapeutic moiety such as acytotoxin, e.g., a cytostatic or cytocidal agent, a therapeutic agent ora radioactive metal ion, e.g., alpha-emitters. A cytotoxin or cytotoxicagent includes any agent that is detrimental to cells.

Further, an antibody or fragment thereof may be conjugated to atherapeutic moiety or drug moiety that modifies a given biologicalresponse. Therapeutic moieties or drug moieties are not to be construedas limited to classical chemical therapeutic agents. For example, thedrug moiety may be a protein, peptide, or polypeptide possessing adesired biological activity. Such proteins may include, for example, atoxin such as abrin, ricin A, pseudomonas exotoxin, cholera toxin, ordiphtheria toxin; a protein such as tumor necrosis factor, α-interferon,β-interferon, nerve growth factor, platelet derived growth factor,tissue plasminogen activator, an apoptotic agent, an anti-angiogenicagent; or, a biological response modifier such as, for example, alymphokine.

Moreover, an antibody can be conjugated to therapeutic moieties such asa radioactive metal ion, such as alpha-emitters such as 213Bi ormacrocyclic chelators useful for conjugating radiometal ions, includingbut not limited to, 131In, 131LU, 131Y, 131Ho, 131Sm, to polypeptides.In certain embodiments, the macrocyclic chelator is1,4,7,10-tetraazacyclododecane-N,N′,N″,N′″-tetraacetic acid (DOTA) whichcan be attached to the antibody via a linker molecule. Such linkermolecules are commonly known in the art and described in Denardo et al.,1998, Clin Cancer Res. 4(10):2483-90; Peterson et al., 1999, Bioconjug.Chem. 10(4):553-7; and Zimmerman et al., 1999, Nucl. Med. Biol.26(8):943-50, each incorporated by reference in their entireties.

Techniques for conjugating therapeutic moieties to antibodies are wellknown, see, e.g., Arnon et al., “Monoclonal Antibodies ForImmunotargeting Of Drugs In Cancer Therapy”, in Monoclonal AntibodiesAnd Cancer Therapy, Reisfeld et al. (eds.), pp. 243-56 (Alan R. Liss,Inc. 1985); Hellstrom et al., “Antibodies For Drug Delivery”, inControlled Drug Delivery (2nd Ed.), Robinson et al. (eds.), pp. 623-53(Marcel Dekker, Inc. 1987); Thorpe, “Antibody Carriers Of CytotoxicAgents In Cancer Therapy: A Review”, in Monoclonal Antibodies 84:Biological And Clinical Applications, Pinchera et al. (eds.), pp.475-506 (1985); “Analysis, Results, And Future Prospective Of TheTherapeutic Use Of Radiolabeled Antibody In Cancer Therapy”, inMonoclonal Antibodies For Cancer Detection And Therapy, Baldwin et al.(eds.), pp. 303-16 (Academic Press 1985), and Thorpe et al., 1982,Immunol. Rev. 62:119-58.

Antibodies may also be attached to solid supports, which areparticularly useful for immunoassays or purification of the targetantigen. Such solid supports include, but are not limited to, glass,cellulose, polyacrylamide, nylon, polystyrene, polyvinyl chloride orpolypropylene.

Methods of Producing Antibodies of the Invention

Nucleic Acids Encoding the Antibodies

The invention provides substantially purified nucleic acid moleculeswhich encode polypeptides comprising segments or domains of theEpo-binding antibody chains described above. Some of the nucleic acidsof the invention comprise the nucleotide sequence encoding the heavychain variable region shown in SEQ ID NO: 13, 33, 53, or 73, and/or thenucleotide sequence encoding the light chain variable region shown inSEQ ID NO: 14, 34, 54, or 74. In a specific embodiment, the nucleic acidmolecules are those identified in Table 1. Some other nucleic acidmolecules of the invention comprise nucleotide sequences that aresubstantially identical (e.g., at least 65, 80%, 95%, or 99%) to thenucleotide sequences of those identified in Table 1. When expressed fromappropriate expression vectors, polypeptides encoded by thesepolynucleotides are capable of exhibiting Epo antigen binding capacity.

Also provided in the invention are polynucleotides which encode at leastone CDR region and usually all three CDR regions from the heavy or lightchain of the Epo-binding antibody set forth above. Some otherpolynucleotides encode all or substantially all of the variable regionsequence of the heavy chain and/or the light chain of the Epo-bindingantibody set forth above. Because of the degeneracy of the code, avariety of nucleic acid sequences will encode each of the immunoglobulinamino acid sequences.

The nucleic acid molecules of the invention can encode both a variableregion and a constant region of the antibody. Some of nucleic acidsequences of the invention comprise nucleotides encoding a mature heavychain sequence that is substantially identical (e.g., at least 80%, 85%90%, 95%, 96%, 97%, 98% or 99%) to the mature heavy chain sequence setforth in SEQ ID NO: 15, 35, 55, or 75. Some other nucleic acid sequencescomprising nucleotide encoding a mature light chain sequence that issubstantially identical (e.g., at least 80%, 85%, 90%, 95%, 96%, 97%,98% or 99%) to the mature light chain sequence set forth in SEQ ID NO:16, 36, 56, or 76.

The polynucleotide sequences can be produced by de novo solid-phase DNAsynthesis or by PCR mutagenesis of an existing sequence (e.g., sequencesas described in the Examples below) encoding an Epo-binding antibody orits binding fragment. Direct chemical synthesis of nucleic acids can beaccomplished by methods known in the art, such as the phosphotriestermethod of Narang et al., 1979, Meth. Enzymol. 68:90; the phosphodiestermethod of Brown et al., Meth. Enzymol. 68:109, 1979; thediethylphosphoramidite method of Beaucage et al., Tetra. Lett., 22:1859,1981; and the solid support method of U.S. Pat. No. 4,458,066.Introducing mutations to a polynucleotide sequence by PCR can beperformed as described in, e.g., PCR Technology: Principles andApplications for DNA Amplification, H. A. Erlich (Ed.), Freeman Press,NY, N.Y., 1992; PCR Protocols: A Guide to Methods and Applications,Innis et al. (Ed.), Academic Press, San Diego, Calif., 1990; Mattila etal., Nucleic Acids Res. 19:967, 1991; and Eckert et al., PCR Methods andApplications 1:17, 1991.

Also provided in the invention are expression vectors and host cells forproducing the Epo-binding antibodies described above. Various expressionvectors can be employed to express the polynucleotides encoding theEpo-binding antibody chains or binding fragments. Both viral-based andnon-viral expression vectors can be used to produce the antibodies in amammalian host cell. Non-viral vectors and systems include plasmids,episomal vectors, typically with an expression cassette for expressing aprotein or RNA, and human artificial chromosomes (see, e.g., Harringtonet al., Nat Genet 15:345, 1997). For example, non-viral vectors usefulfor expression of the Epo-binding polynucleotides and polypeptides inmammalian (e.g., human) cells include pThioHis A, B & C, pcDNA3.1/His,pEBVHis A, B & C, (Invitrogen, San Diego, Calif.), MPSV vectors, andnumerous other vectors known in the art for expressing other proteins.Useful viral vectors include vectors based on retroviruses,adenoviruses, adenoassociated viruses, herpes viruses, vectors based onSV40, papilloma virus, HBP Epstein Barr virus, vaccinia virus vectorsand Semliki Forest virus (SFV). See, Brent et al., supra; Smith, Annu.Rev. Microbiol. 49:807, 1995; and Rosenfeld et al., Cell 68:143, 1992.

The choice of expression vector depends on the intended host cells inwhich the vector is to be expressed. Typically, the expression vectorscontain a promoter and other regulatory sequences (e.g., enhancers) thatare operably linked to the polynucleotides encoding an Epo-bindingantibody chain or fragment. In some embodiments, an inducible promoteris employed to prevent expression of inserted sequences except underinducing conditions. Inducible promoters include, e.g., arabinose, lacZ,metallothionein promoter or a heat shock promoter. Cultures oftransformed organisms can be expanded under non-inducing conditionswithout biasing the population for coding sequences whose expressionproducts are better tolerated by the host cells. In addition topromoters, other regulatory elements may also be required or desired forefficient expression of an Epo-binding antibody chain or fragment. Theseelements typically include an ATG initiation codon and adjacent ribosomebinding site or other sequences. In addition, the efficiency ofexpression may be enhanced by the inclusion of enhancers appropriate tothe cell system in use (see, e.g., Scharf et al., Results Probl. CellDiffer. 20:125, 1994; and Bittner et al., Meth. Enzymol., 153:516,1987). For example, the SV40 enhancer or CMV enhancer may be used toincrease expression in mammalian host cells.

The expression vectors may also provide a secretion signal sequenceposition to form a fusion protein with polypeptides encoded by insertedEpo-binding antibody sequences. More often, the inserted Epo-bindingantibody sequences are linked to a signal sequences before inclusion inthe vector. Vectors to be used to receive sequences encoding Epo-bindingantibody light and heavy chain variable domains sometimes also encodeconstant regions or parts thereof. Such vectors allow expression of thevariable regions as fusion proteins with the constant regions therebyleading to production of intact antibodies or fragments thereof.Typically, such constant regions are human.

The host cells for harboring and expressing the Epo-binding antibodychains can be either prokaryotic or eukaryotic. E. coli is oneprokaryotic host useful for cloning and expressing the polynucleotidesof the present invention. Other microbial hosts suitable for use includebacilli, such as Bacillus subtilis, and other enterobacteriaceae, suchas Salmonella, Serratia, and various Pseudomonas species. In theseprokaryotic hosts, one can also make expression vectors, which typicallycontain expression control sequences compatible with the host cell(e.g., an origin of replication). In addition, any number of a varietyof well-known promoters will be present, such as the lactose promotersystem, a tryptophan (trp) promoter system, a beta-lactamase promotersystem, or a promoter system from phage lambda. The promoters typicallycontrol expression, optionally with an operator sequence, and haveribosome binding site sequences and the like, for initiating andcompleting transcription and translation. Other microbes, such as yeast,can also be employed to express Epo-binding polypeptides of theinvention. Insect cells in combination with baculovirus vectors can alsobe used.

In some preferred embodiments, mammalian host cells are used to expressand produce the Epo -binding polypeptides of the present invention. Forexample, they can be either a hybridoma cell line expressing endogenousimmunoglobulin genes (e.g., the 1D6.C9 myeloma hybridoma clone asdescribed in the Examples) or a mammalian cell line harboring anexogenous expression vector (e.g., the SP2/0 myeloma cells exemplifiedbelow). These include any normal mortal or normal or abnormal immortalanimal or human cell. For example, a number of suitable host cell linescapable of secreting intact immunoglobulins have been developedincluding the CHO cell lines, various Cos cell lines, HeLa cells,myeloma cell lines, transformed B-cells and hybridomas. The use ofmammalian tissue cell culture to express polypeptides is discussedgenerally in, e.g., Winnacker, FROM GENES TO CLONES, VCH Publishers,N.Y., N.Y., 1987. Expression vectors for mammalian host cells caninclude expression control sequences, such as an origin of replication,a promoter, and an enhancer (see, e.g., Queen, et al., Immunol. Rev.89:49-68, 1986), and necessary processing information sites, such asribosome binding sites, RNA splice sites, polyadenylation sites, andtranscriptional terminator sequences. These expression vectors usuallycontain promoters derived from mammalian genes or from mammalianviruses. Suitable promoters may be constitutive, cell type-specific,stage-specific, and/or modulatable or regulatable. Useful promotersinclude, but are not limited to, the metallothionein promoter, theconstitutive adenovirus major late promoter, the dexamethasone-inducibleMMTV promoter, the SV40 promoter, the MRP poIIII promoter, theconstitutive MPSV promoter, the tetracycline-inducible CMV promoter(such as the human immediate-early CMV promoter), the constitutive CMVpromoter, and promoter-enhancer combinations known in the art.

Methods for introducing expression vectors containing the polynucleotidesequences of interest vary depending on the type of cellular host. Forexample, calcium chloride transfection is commonly utilized forprokaryotic cells, whereas calcium phosphate treatment orelectroporation may be used for other cellular hosts. (See generallySambrook, et al., supra). Other methods include, e.g., electroporation,calcium phosphate treatment, liposome-mediated transformation, injectionand microinjection, ballistic methods, virosomes, immunoliposomes,polycation:nucleic acid conjugates, naked DNA, artificial virions,fusion to the herpes virus structural protein VP22 (Elliot and O'Hare,Cell 88:223, 1997), agent-enhanced uptake of DNA, and ex vivotransduction. For long-term, high-yield production of recombinantproteins, stable expression will often be desired. For example, celllines which stably express Epo-binding antibody chains or bindingfragments can be prepared using expression vectors of the inventionwhich contain viral origins of replication or endogenous expressionelements and a selectable marker gene. Following the introduction of thevector, cells may be allowed to grow for 1-2 days in an enriched mediabefore they are switched to selective media. The purpose of theselectable marker is to confer resistance to selection, and its presenceallows growth of cells which successfully express the introducedsequences in selective media. Resistant, stably transfected cells can beproliferated using tissue culture techniques appropriate to the celltype.

Generation of Monoclonal Antibodies of the Invention

Monoclonal antibodies (mAbs) can be produced by a variety of techniques,including conventional monoclonal antibody methodology e.g., thestandard somatic cell hybridization technique of Kohler and Milstein,1975 Nature 256: 495. Many techniques for producing monoclonal antibodycan be employed e.g., viral or oncogenic transformation of Blymphocytes.

Animal systems for preparing hybridomas include the murine, rat andrabbit systems. Hybridoma production in the mouse is a well-establishedprocedure. Immunization protocols and techniques for isolation ofimmunized splenocytes for fusion are known in the art. Fusion partners(e.g., murine myeloma cells) and fusion procedures are also known.

Chimeric or humanized antibodies of the present invention can beprepared based on the sequence of a murine monoclonal antibody preparedas described above. DNA encoding the heavy and light chainimmunoglobulins can be obtained from the murine hybridoma of interestand engineered to contain non-murine (e.g.,. human) immunoglobulinsequences using standard molecular biology techniques. For example, tocreate a chimeric antibody, the murine variable regions can be linked tohuman constant regions using methods known in the art (see e.g., U.S.Pat. No. 4,816,567 to Cabilly et al.). To create a humanized antibody,the murine CDR regions can be inserted into a human framework usingmethods known in the art. See e.g., U.S. Pat. No. 5,225,539 to Winter,and U.S. Pat. Nos. 5,530,101; 5,585,089; 5,693,762 and 6,180,370 toQueen et al.

In a certain embodiment, the antibodies of the invention are humanmonoclonal antibodies. Such human monoclonal antibodies directed againstEpo can be generated using transgenic or transchromosomic mice carryingparts of the human immune system rather than the mouse system. Thesetransgenic and transchromosomic mice include mice referred to herein asHuMAb mice and KM mice, respectively, and are collectively referred toherein as “human Ig mice.”

The HuMAb mouse® (Medarex, Inc.) contains human immunoglobulin geneminiloci that encode un-rearranged human heavy (p and y) and K lightchain immunoglobulin sequences, together with targeted mutations thatinactivate the endogenous p and K chain loci (see e.g., Lonberg, et al.,1994 Nature 368(6474): 856-859). Accordingly, the mice exhibit reducedexpression of mouse IgM or κ, and in response to immunization, theintroduced human heavy and light chain transgenes undergo classswitching and somatic mutation to generate high affinity human IgGκmonoclonal (Lonberg, N. et al., 1994 supra; reviewed in Lonberg, N.,1994 Handbook of Experimental Pharmacology 113:49-101; Lonberg, N. andHuszar, D., 1995 Intern. Rev. Immunol. 13: 65-93, and Harding, F. andLonberg, N., 1995 Ann. N. Y. Acad. Sci. 764:536-546). The preparationand use of HuMAb mice, and the genomic modifications carried by suchmice, is further described in Taylor, L. et al., 1992 Nucleic AcidsResearch 20:6287-6295; Chen, J. et at., 1993 International Immunology 5:647-656; Tuaillon et al., 1993 Proc. Natl. Acad. Sci. USA 94:3720-3724;Choi et al., 1993 Nature Genetics 4:117-123; Chen, J. et al., 1993 EMBOJ. 12: 821-830; Tuaillon et al., 1994 J. Immunol. 152:2912-2920; Taylor,L. et al., 1994 International Immunology 579-591; and Fishwild, D. etal., 1996 Nature Biotechnology 14: 845-851, the contents of all of whichare hereby specifically incorporated by reference in their entirety. Seefurther, U.S. Pat. Nos. 5,545,806; 5,569,825; 5,625,126; 5,633,425;5,789,650; 5,877,397; 5,661,016; 5,814,318; 5,874,299; and 5,770,429;all to Lonberg and Kay; U.S. Pat. No. 5,545,807 to Surani et al.; PCTPublication Nos. WO 92103918, WO 93/12227, WO 94/25585, WO 97113852, WO98/24884 and WO 99/45962, all to Lonberg and Kay; and PCT PublicationNo. WO 01/14424 to Korman et al.

In another embodiment, human antibodies of the invention can be raisedusing a mouse that carries human immunoglobulin sequences on transgenesand transchromosomes such as a mouse that carries a human heavy chaintransgene and a human light chain transchromosome. Such mice, referredto herein as “KM mice”, are described in detail in PCT Publication WO02/43478 to Ishida et al.

Still further, alternative transgenic animal systems expressing humanimmunoglobulin genes are available in the art and can be used to raiseEpo -binding antibodies of the invention. For example, an alternativetransgenic system referred to as the Xenomouse (Abgenix, Inc.) can beused. Such mice are described in, e.g., U.S. Pat. Nos. 5,939,598;6,075,181; 6,114,598; 6,150,584 and 6,162,963 to Kucherlapati et al.

Moreover, alternative transchromosomic animal systems expressing humanimmunoglobulin genes are available in the art and can be used to raiseEpo-binding antibodies of the invention. For example, mice carrying botha human heavy chain transchromosome and a human light chaintranschromosome, referred to as “TC mice” can be used; such mice aredescribed in Tomizuka et al., 2000 Proc. Natl. Acad. Sci. USA97:722-727. Furthermore, cows carrying human heavy and light chaintranschromosomes have been described in the art (Kuroiwa et al., 2002Nature Biotechnology 20:889-894) and can be used to raise Epo-bindingantibodies of the invention.

Human monoclonal antibodies of the invention can also be prepared usingphage display methods for screening libraries of human immunoglobulingenes. Such phage display methods for isolating human antibodies areestablished in the art or described in the examples below. See forexample: U.S. Pat. Nos. 5,223,409; 5,403,484; and 5,571,698 to Ladner etal.; U.S. Pat. Nos. 5,427,908 and 5,580,717 to Dower et al.; U.S. Pat.Nos. 5,969,108 and 6,172,197 to McCafferty et al.; and U.S. Pat. Nos.5,885,793; 6,521,404; 6,544,731; 6,555,313; 6,582,915 and 6,593,081 toGriffiths et al.

Human monoclonal antibodies of the invention can also be prepared usingSCID mice into which human immune cells have been reconstituted suchthat a human antibody response can be generated upon immunization. Suchmice are described in, for example, U.S. Pat. Nos. 5,476,996 and5,698,767 to Wilson et al.

Framework or Fc Engineering

Engineered antibodies of the invention include those in whichmodifications have been made to framework residues within VH and/or VL,e.g. to improve the properties of the antibody. Typically such frameworkmodifications are made to decrease the immunogenicity of the antibody.For example, one approach is to “backmutate” one or more frameworkresidues to the corresponding germline sequence. More specifically, anantibody that has undergone somatic mutation may contain frameworkresidues that differ from the germline sequence from which the antibodyis derived. Such residues can be identified by comparing the antibodyframework sequences to the germline sequences from which the antibody isderived. To return the framework region sequences to their germlineconfiguration, the somatic mutations can be “backmutated” to thegermline sequence by, for example, site-directed mutagenesis. Such“backmutated” antibodies are also intended to be encompassed by theinvention.

Another type of framework modification involves mutating one or moreresidues within the framework region, or even within one or more CDRregions, to remove T cell-epitopes so thereby reduce the potentialimmunogenicity of the antibody. This approach is also referred to as“deimmunization” and is described in further detail in U.S. PatentPublication No. 20030153043 by Carr et al.

In addition or alternative to modifications made within the framework orCDR regions, antibodies of the invention may be engineered to includemodifications within the Fc region, typically to alter one or morefunctional properties of the antibody, such as serum half-life,complement fixation, Fc receptor binding, and/or antigen-dependentcellular cytotoxicity. Furthermore, an antibody of the invention may bechemically modified (e.g., one or more chemical moieties can be attachedto the antibody) or be modified to alter its glycosylation, again toalter one or more functional properties of the antibody. Each of theseembodiments is described in further detail below. The numbering ofresidues in the Fc region is that of the EU index of Kabat.

In one embodiment, the hinge region of CH1 is modified such that thenumber of cysteine residues in the hinge region is altered, e.g.,increased or decreased. This approach is described further in U.S. Pat.No. 5,677,425 by Bodmer et al. The number of cysteine residues in thehinge region of CH1 is altered to, for example, facilitate assembly ofthe light and heavy chains or to increase or decrease the stability ofthe antibody.

In another embodiment, the Fc hinge region of an antibody is mutated todecrease the biological half-life of the antibody. More specifically,one or more amino acid mutations are introduced into the CH2-CH3 domaininterface region of the Fc-hinge fragment such that the antibody hasimpaired Staphylococcyl protein A (SpA) binding relative to nativeFc-hinge domain SpA binding. This approach is described in furtherdetail in U.S. Pat. No. 6,165,745 by Ward et al.

In another embodiment, the antibody is modified to increase itsbiological half-life. Various approaches are possible. For example, oneor more of the following mutations can be introduced: T252L, T254S,T256F, as described in U.S. Pat. No. 6,277,375 to Ward. Alternatively,to increase the biological half-life, the antibody can be altered withinthe CH1 or CL region to contain a salvage receptor binding epitope takenfrom two loops of a CH2 domain of an Fc region of an IgG, as describedin U.S. Pat. Nos. 5,869,046 and 6,121,022 by Presta et al.

In yet other embodiments, the Fc region is altered by replacing at leastone amino acid residue with a different amino acid residue to alter theeffector functions of the antibody. For example, one or more amino acidscan be replaced with a different amino acid residue such that theantibody has an altered affinity for an effector ligand but retains theantigen-binding ability of the parent antibody. The effector ligand towhich affinity is altered can be, for example, an Fc receptor or the C1component of complement. This approach is described in further detail inU.S. Pat. Nos. 5,624,821 and 5,648,260, both by Winter et al.

In another embodiment, one or more amino acids selected from amino acidresidues can be replaced with a different amino acid residue such thatthe antibody has altered C1q binding and/or reduced or abolishedcomplement dependent cytotoxicity (CDC). This approach is described infurther detail in U.S. Pat. No. 6,194,551 by Idusogie et al.

In another embodiment, one or more amino acid residues are altered tothereby alter the ability of the antibody to fix complement. Thisapproach is described further in PCT Publication WO 94/29351 by Bodmeret al.

In yet another embodiment, the Fc region is modified to increase theability of the antibody to mediate antibody dependent cellularcytotoxicity (ADCC) and/or to increase the affinity of the antibody foran Fcy receptor by modifying one or more amino acids. This approach isdescribed further in PCT Publication WO 00/42072 by Presta. Moreover,the binding sites on human IgG1 for FcyRI, FcyRII, FcyRIII and FcRn havebeen mapped and variants with improved binding have been described (seeShields, R. L. et al., 2001 J. Biol. Chen. 276:6591-6604).

In still another embodiment, the glycosylation of an antibody ismodified. For example, an aglycoslated antibody can be made (i.e., theantibody lacks glycosylation). Glycosylation can be altered to, forexample, increase the affinity of the antibody for “antigen’. Suchcarbohydrate modifications can be accomplished by, for example, alteringone or more sites of glycosylation within the antibody sequence. Forexample, one or more amino acid substitutions can be made that result inelimination of one or more variable region framework glycosylation sitesto thereby eliminate glycosylation at that site. Such aglycosylation mayincrease the affinity of the antibody for antigen. Such an approach isdescribed in further detail in U.S. Pat. Nos. 5,714,350 and 6,350,861 byCo et al.

Additionally or alternatively, an antibody can be made that has analtered type of glycosylation, such as a hypofucosylated antibody havingreduced amounts of fucosyl residues or an antibody having increasedbisecting GlcNac structures. Such altered glycosylation patterns havebeen demonstrated to increase the ADCC ability of antibodies. Suchcarbohydrate modifications can be accomplished by, for example,expressing the antibody in a host cell with altered glycosylationmachinery. Cells with altered glycosylation machinery have beendescribed in the art and can be used as host cells in which to expressrecombinant antibodies of the invention to thereby produce an antibodywith altered glycosylation. For example, EP 1,176,195 by Hang et al.describes a cell line with a functionally disrupted FUT8 gene, whichencodes a fucosyl transferase, such that antibodies expressed in such acell line exhibit hypofucosylation. PCT Publication WO 03/035835 byPresta describes a variant CHO cell line, Lecl3 cells, with reducedability to attach fucose to Asn(297)-linked carbohydrates, alsoresulting in hypofucosylation of antibodies expressed in that host cell(see also Shields, R. L. et al., 2002 J. Biol. Chem. 277:26733-26740).PCT Publication WO 99/54342 by Umana et al. describes cell linesengineered to express glycoprotein-modifying glycosyl transferases(e.g., beta(1,4)-N acetylglucosaminyltransferase III (GnTIII)) such thatantibodies expressed in the engineered cell lines exhibit increasedbisecting GlcNac structures which results in increased ADCC activity ofthe antibodies (see also Umana et al., 1999 Nat. Biotech. 17:176-180).

Methods of Engineering Altered Antibodies

As discussed above, the Epo-binding antibodies having VH and VLsequences or full length heavy and light chain sequences shown hereincan be used to create new Epo-binding antibodies by modifying fulllength heavy chain and/or light chain sequences, VH and/or VL sequences,or the constant region(s) attached thereto. Thus, in another aspect ofthe invention, the structural features of an Epo-binding antibody of theinvention are used to create structurally related Epo-binding antibodiesthat retain at least one functional property of the antibodies of theinvention, such as binding to human Epo and also inhibiting one or morefunctional properties of Epo (e.g., inhibit Epo binding to the Eporeceptor, inhibit Epo-dependent cell proliferation).

For example, one or more CDR regions of the antibodies of the presentinvention, or mutations thereof, can be combined recombinantly withknown framework regions and/or other CDRs to create additional,recombinantly-engineered, Epo-binding antibodies of the invention, asdiscussed above. Other types of modifications include those described inthe previous section. The starting material for the engineering methodis one or more of the VH and/or VL sequences provided herein, or one ormore CDR regions thereof. To create the engineered antibody, it is notnecessary to actually prepare (i.e., express as a protein) an antibodyhaving one or more of the VH and/or VL sequences provided herein, or oneor more CDR regions thereof. Rather, the information contained in thesequence(s) is used as the starting material to create a “secondgeneration” sequence(s) derived from the original sequence(s) and thenthe “second generation” sequence(s) is prepared and expressed as aprotein.

Accordingly, in another embodiment, the invention provides a method forpreparing a modified Epo-binding antibody comprising the steps of: a)producing and Epo-binding antibody comprising a heavy chain variableregion antibody sequence having a CDR1 sequence selected from the groupconsisting of SEQ ID NOs: 1, 21, 41, and 61, a CDR2 sequence selectedfrom the group consisting of SEQ ID NOs: 2, 22, 42, and 62, and/or aCDR3 sequence selected from the group consisting of SEQ ID NOs: 3, 23,43, and 63; and a light chain variable region antibody sequence having aCDR1 sequence selected from the group consisting of SEQ ID NOs: 4, 24,44, and 64, a CDR2 sequence selected from the group consisting of SEQ IDNOs: 5, 25, 45, and 65, and/or a CDR3 sequence selected from the groupconsisting of SEQ ID NOs: 6, 26, 46, and 66; b) altering at least oneamino acid residue within the heavy chain variable region antibodysequence and/or the light chain variable region antibody sequence tocreate at least one altered antibody sequence; and c) expressing thealtered antibody sequence as a protein.

Accordingly, in another embodiment, the invention provides a method forpreparing an Epo-binding antibody consisting of a heavy chain variableregion antibody sequence having a CDR1 sequence selected from the groupconsisting of SEQ ID NOs: 7, 27, 47, and 67, a CDR2 sequence selectedfrom the group consisting of SEQ ID NOs: 8, 28, 48, and 68, and/or aCDR3 sequence selected from the group consisting of SEQ ID NOs: 9, 29,49, and 69; and a light chain variable region antibody sequence having aCDR1 sequence selected from the group consisting of SEQ ID NOs: 10, 30,50, and 70, a CDR2 sequence selected from the group consisting of SEQ IDNOs: 11, 31, 51, and 71, and/or a CDR3 sequence selected from the groupconsisting of SEQ ID NOs: 12, 32, 52, and 72; altering at least oneamino acid residue within the heavy chain variable region antibodysequence and/or the light chain variable region antibody sequence tocreate at least one altered antibody sequence; and expressing thealtered antibody sequence as a protein.

Accordingly, in another embodiment, the invention provides a method forpreparing an Epo-binding antibody optimized for expression in amammalian cell consisting of: a full length heavy chain antibodysequence having a sequence selected from the group of SEQ ID NOs: 15,35, 55 and 75; and a full length light chain antibody sequence having asequence selected from the group of SEQ ID NOs: 16, 36, 56, and 76;altering at least one amino acid residue within the full length heavychain antibody sequence and/or the full length light chain antibodysequence to create at least one altered antibody sequence; andexpressing the altered antibody sequence as a protein. In oneembodiment, the alteration of the heavy or light chain is in theframework region of the heavy or light chain.

The altered antibody sequence can also be prepared by screening antibodylibraries having fixed CDR3 sequences or minimal essential bindingdeterminants as described in US20050255552 and diversity on CDR1 andCDR2 sequences. The screening can be performed according to anyscreening technology appropriate for screening antibodies from antibodylibraries, such as phage display technology.

Standard molecular biology techniques can be used to prepare and expressthe altered antibody sequence. The antibody encoded by the alteredantibody sequence(s) is one that retains one, some or all of thefunctional properties of the Epo-binding antibodies described herein,which functional properties include, but are not limited to,specifically binding to human, cynomolgus, rat, and/or mouse Epo; andthe antibody inhibit Epo-dependent cell proliferation in a F36E and/orBa/F3-EpoR cell proliferation assay.

In certain embodiments of the methods of engineering antibodies of theinvention, mutations can be introduced randomly or selectively along allor part of an Epo-binding antibody coding sequence and the resultingmodified Epo-binding antibodies can be screened for binding activityand/or other functional properties as described herein. Mutationalmethods have been described in the art. For example, PCT Publication WO02/092780 by Short describes methods for creating and screening antibodymutations using saturation mutagenesis, synthetic ligation assembly, ora combination thereof. Alternatively, PCT Publication WO 03/074679 byLazar et al. describes methods of using computational screening methodsto optimize physiochemical properties of antibodies.

In certain embodiments of the invention antibodies have been engineeredto remove sites of deamidation. Deamidation is known to cause structuraland functional changes in a peptide or protein. Deamidation can resultin decreased bioactivity, as well as alterations in pharmacokinetics andantigenicity of the protein pharmaceutical. (Anal Chem. 2005 Mar. 1;77(5):1432-9).

In certain embodiments of the invention the antibodies have beenengineered to increase pl and improve their drug-like properties. The plof a protein is a key determinant of the overall biophysical propertiesof a molecule. Antibodies that have low pls have been known to be lesssoluble, less stable, and prone to aggregation. Further, thepurification of antibodies with low pl is challenging and can beproblematic especially during scale-up for clinical use. Increasing thepl of the anti-Epo antibodies, or Fabs, of the invention improved theirsolubility, enabling the antibodies to be formulated at higherconcentrations (>100 mg/ml). Formulation of the antibodies at highconcentrations (e.g. >100mg/ml) offers the advantage of being able toadminister higher doses of the antibodies into eyes of patients viaintravitreal injections, which in turn may enable reduced dosingfrequency, a significant advantage for treatment of chronic diseasesincluding retinal vascular diseases. Higher pls may also increase theFcRn-mediated recycling of the IgG version of the antibody thus enablingthe drug to persist in the body for a longer duration, requiring fewerinjections. Finally, the overall stability of the antibodies issignificantly improved due to the higher pl resulting in longershelf-life and bioactivity in vivo. Preferably, the pl is greater thanor equal to 8.2.

The functional properties of the altered antibodies can be assessedusing standard assays available in the art and/or described herein, suchas those set forth in the Examples (e.g., ELISAs).

Prophylactic and Therapeutic Uses

Antibodies that binds Epo as described herein, can be used at atherapeutically useful concentration for the treatment of a disease ordisorder associated with increased Epo levels and/or activity byadministering to a subject in need thereof an effective amount of theantibodies or antigen binding fragments of the invention. The presentinvention provides a method of treating conditions or disordersassociated with retinal vascular disease by administering to a subjectin need thereof an effective amount of the antibodies of the invention.The present invention provides a method of treating conditions ordisorders associated with diabetic retinopathy (DR) by administering toa subject in need thereof an effective amount of the antibodies of theinvention. The present invention provides a method of treatingconditions or disorders associated with macular edema administering to asubject in need thereof an effective amount of the antibodies of theinvention. The invention also provides a method of treating diabeticmacular edema (DME) by administering to a subject in need thereof aneffective amount of the antibodies of the invention. The presentinvention further provides a method of treating proliferative diabeticretinopathy (PDR) by administering to a subject in need thereof aneffective amount of the antibodies of the invention. Still further, thepresent invention provides methods for treating age-related macularedema (AMD), retinal vein occlusion (RVO), angioedema, multifocalchoroiditis, myopic choroidal neovascularization, and/or retinopathy ofprematurity, by administering to a subject in need thereof an effectiveamount of the antibodies of the invention. The invention also providesmethods of treating beta thelassemia and/or cancer.

The invention also relates to a composition comprising an isolatedantibody or antigen binding fragment thereof as described herein for usein treating a disease or disorder associated with increased Epo levelsand/or activity. The invention further relates to a compositioncomprising an isolated antibody or antigen binding fragment thereof asdescribed herein for use in treating conditions or disorders associatedwith retinal vascular disease. The invention further relates to acomposition comprising an isolated antibody or antigen binding fragmentthereof as described herein for use in treating conditions or disordersassociated with diabetic retinopathy (DR). The invention further relatesto a composition comprising an isolated antibody or antigen bindingfragment thereof as described herein for use in treating conditions ordisorders associated with macular edema, diabetic macular edema (DME),and/or proliferative diabetic retinopathy (PDR). The invention stillfurther relates to a composition comprising an isolated antibody orantigen binding fragment thereof as described herein for use age-relatedmacular edema (AMD), retinal vein occlusion (RVO), angioedema,multifocal choroiditis, myopic choroidal neovascularization, and/orretinopathy of prematurity. The invention further relates to acomposition comprising an isolated antibody or antigen binding fragmentthereof as described herein for use in treating beta thelassemia and/orcancer. More specifically, the isolated antibody or antigen bindingfragment thereof as described herein for use in treating a disease ordisorder associated with increased Epo levels and/or activity, may beany one of the antibodies or antigen binding fragments described herein,in addition to those described in Table 1. Still further, the isolatedantibody or antigen binding fragment thereof as described herein for usein treating conditions or disorders associated with retinal vasculardisease, may be any one of the antibodies or antigen binding fragmentsdescribed herein, in addition to those described in Table 1.Theantibodies of the invention can be used, inter alia, to preventprogression of conditions or disorders associated with retinal vasculardisease (for example, DR, DME, NPDR, PDR, age-related maculardegeneration (AMD), retinal vein occlusion (RVO), angioedema, multifocalchoroiditis, myopic choroidal neovascularization, and/or retinopathy ofprematurity), to treat or prevent macular edema associated with retinalvascular disease, to reduce the frequency of Lucentis® (RTM) injection,and to improve vision lost due to retinal vascular disease progression.The antibodies of the invention can also be used in combination withanti-VEGF therapies for the treatment of patients with retinal vasculardisease.

In one aspect, the invention relates to a method of inhibitingEpo-dependent cell proliferation wherein the method includes the step ofcontacting Epo (e.g., contacting Epo in a subject) with an effectiveamount of a composition comprising the isolated antibody or antigenbinding fragments thereof described herein; in particular, thecomposition can comprise the antibody NVS1, NVS2, NVS3, or NVS4. In oneaspect, the method comprises contacting a cell (e.g., a cell comprisingEpo) with a composition coprising the isolated antibody or antigenbinding fragment thereof as described herein. The invention also relatesto a composition comprising an isolated antibody or antigen bindingfragment thereof as described herein for use to inhibit Epo-dependentcell proliferation in a subject. It is contemplated that the cell is ahuman cell. The cell could be a B cell. It is further contemplated thatthe cell is in a subject. It is also contemplated that the cell is inthe eye of the subject. It is still further contemplated that thesubject is human.

Cell proliferation can be measured by, for example, slit-lampbio-microscopt, optical coherence tomography, color fundus photography,and fluorescein angiography (Heng et al. Diabet. Med. 2013 June;30(6):640-50). In addition, the ability of an antibody or antigenbinding fragment described herein to inhibit Epo-dependent cellproliferation can be measured using an assay such as the F36E, orBa/F3-EpoR cell proliferation assay described below.

The invention also relates to a method of inhibiting Epo-dependent cellsignalling wherein the method includes the step of contacting Epo withan effective amount of a composition comprising the isolated antibody orantigen binding fragments thereof described herein to prevent Epo frominteracting with a receptor on a cell surface. In one aspect, the methodcomprises contacting a cell comprising Epo with a composition coprisingthe isolated antibody or antigen binding fragment thereof as describedherein. The invention also relates to a composition comprising anisolated antibody or antigen binding fragment thereof as describedherein for use to inhibit Epo-dependent cell signalling in a subject. Itis contemplated that the cell is a human cell. It is furthercontemplated that the cell is in a subject. It is also contemplated thatthe cell is in the eye of the subject. It is still further contemplatedthat the subject is human.

Binding of Epo to the EpoR induces signaling via JAK2 kinases that leadto activation of downstream signaling pathways that includephosphatidyl-inositol 3-kinase (PI-3K)/Akt, MAP kinase, STATS andprotein kinase C (Jelkmann, 2007; Jelkmann, 2004). Epo or the Eporeceptor (EpoR) have been reported to be produced endogenously bydifferent cell types such as endothelial cells, smooth muscle cells, andCNS cells (Ogunshola and Bogdanova, 2013). Activation of EpoR uponbinding of Epo can trigger downstream signalling pathways leading todifferent activities such as calcium transport (Korbel et al., 2004),cell survival (Velly et al., 2010), neuroprotection (Grimm et al.,2002), and angiogenesis (Ribatti, 2010; Ribatti et al., 2003).Accordingly, inhibition of Epo-dependent cell signaling can bedetermined by measuring the activity of one or more of these signalingpathways. For example, inhibition of Epo-dependent cell signaling can bedetermined by measuring JAK2 kinase, PI-3K/Akt, MAP kinase, STATS orprotein kinase C. Methods for measuring these signaling pathways areknown in the art and kits for measuring such pathway activity arecommercially available. In addition, inhibition of Epo-dependent cellsignaling can be determined by measuring cell proliferation as describedabove. Cell proliferation can be in a subject (e.g., angiogenesis), orcan be measured using an assay such as the F36E, or Ba/F3-EpoR cellproliferation assay described below. In one aspect, Epo-dependent cellsignaling is statistically significantly (p<0.05) decreased in thepresence of an antibody described herein, relative to control.

The invention also relates to a method of inhibiting Epo-dependent cellproliferation or signalling wherein the method includes the step ofcontacting Epo with an effective amount of a composition comprising theisolated antibody or antigen binding fragments thereof described hereinto prevent Epo from interacting with a receptor on a cell surface. It iscontemplated that the cell is a B cell. It is contemplated that the cellis a human cell.

The invention also relates to a method of inhibiting Epo binding to theEpo receptor wherein the method includes the step of contacting Epo(e.g., contacting Epo in a subject) with an effective amount of acomposition comprising the isolated antibody or antigen bindingfragments thereof described herein; in particular, the composition cancomprise the antibody NVS1, NVS2, NVS3, or NVS4. The invention alsorelates to a composition comprising an isolated antibody or antigenbinding fragment thereof as described herein for use to inhibit Epobinding to the Epo receptor on a cell of a subject; in particular, thecomposition can comprise the antibody NVS1, NVS2, NVS3, or NVS4. It iscontemplated that the cell is a human cell. It is further contemplatedthat the cell is in a subject. It is also contemplated that the cell isin the eye of the subject. It is still further contemplated that thesubject is human. Inhibition of Epo binding to the Epo receptor can bemeasured as described by Khankin et al. PLoS ONE, 2010 5:e9246

Treatment and/or prevention of retinal vascular disease and macularedema associated with retinal vascular disease can be determined by anophthalmologist or health care professional using clinically relevantmeasurements of visual function and/or retinal anatomy. Treatment ofconditions or disorders associated with retinal vascular disease meansany action (e.g., administration of an anti-Epo antibody describedherein) that results in, or is contemplated to result in, theimprovement or preservation of visual function and/or retinal anatomy.In addition, prevention as it relates to conditions or disordersassociated with retinal vascular disease means any action (e.g.,administration of an anti-Epo antibody described herein) that preventsor slows a worsening in visual function, retinal anatomy, and/or aretinal vascular disease parameter, as defined herein, in a patient atrisk for said worsening.

Visual function may include, for example, visual acuity, visual acuitywith low illumination, visual field, central visual field, peripheralvision, contrast sensitivity, dark adaptation, photostress recovery,color discrimination, reading speed, dependence on assistive devices(e.g., large typeface, magnifying devices, telescopes), facialrecognition, proficiency at operating a motor vehicle, ability toperform one or more activities of daily living, and/or patient-reportedsatisfaction related to visual function.

Exemplary measures of visual function include Snellen visual acuity,ETDRS visual acuity, low-luminance visual acuity, Amsler grid, Goldmannvisual field, Humphrey visual field, microperimetry, Pelli-Robsoncharts, SKILL card, Ishihara color plates, Farnsworth D15 or D100 colortest, standard electroretinography, multifocal electroretinography,validated tests for reading speed, facial recognition, drivingsimulations, and patient reported satisfaction. Thus, treatment ofvascular disease and/or macular edema can be said to be achieved upon again of or failure to lose 2 or more lines (or 10 letters) of vision onan ETDRS scale. In addition, treatment of vascular disease and/ormacular edema can be said to occur where a subject exhibits at least a10% an increase or lack of 10% decrease in reading speed (words perminute). In addition, treatment of vascular disease and/or macular edemacan be said to occur where a subject exhibits at least a 20% increase orlack of a 20% decrease in the proportion of correctly identified plateson an Ishihara test or correctly sequenced disks on a Farnsworth test.Further, treatment of retinal vascular disease and/or macular edema, canbe said to occur if a subject has, for example, at least 10% decrease orlack of a 10% or more increase in time to a pre-specified degree of darkadaptation. In addition, treatment of retinal vascular disease and/ormacular edema can be said to occur where a subject exhibits, forexample, at least a 10% reduction or lack of a 10% or more increase intotal area of visual scotoma expressed as a visual angle determined by aqualified health care professional (i.e., ophthalmologist).

Undesirable aspects of retinal anatomy that may be treated or preventedinclude, for example, microaneurysm, macular edema, cotton-wool spot,intraretinal microvascular abnormality (IRMA), capillary dropout,leukocyte adhesion, retinal ischemia, neovascularization of the opticdisk, neovascularization of the posterior pole, iris neovascularization,intraretinal hemorrhage, vitreous hemorrhage, macular scar, subretinalfibrosis, and retinal fibrosis, venous dilation, vascular tortuosity,vascular leakage. Thus, treatment of, for example, macular edema can bedetermined by a 20% or more reduction in thickness of the centralretinal sub-field as measured by optical coherence tomography.

Exemplary means of assessing retinal anatomy include funduscopy, fundusphotography, fluorescein angiography, indocyanine green angiography,optical coherence tomography (OCT), spectral domain optical coherencetomography, scanning laser ophthalmoscopy, confocal microscopy, adaptiveoptics, fundus autofluorescence, biopsy, necropsy, andimmunohistochemistry. Thus, vascular disease and/or macular edema can besaid to be treated in a subject upon a 10% reduction in leakage area asdetermined by fluorescein angiography.

Subjects to be treated with therapeutic agents of the present inventioncan also be administered other therapeutic agents with known methods oftreating conditions associated with diabetes mellitus, such as all formsof insulin and anti-hypertensive medications.

Treatment and/or prevention of ocular disease such as age-relatedmacular degeneration (AMD), retinal vein occlusion (RVO), angioedema,multifocal choroiditis, myopic choroidal neovascularization, and/orretinopathy of prematurity can be determined by an ophthalmologist orhealth care professional using clinically relevant measurements ofvisual function and/or retinal anatomy by any of the measures describedabove. Although the measures described herein don't apply to each andevery ocular disease herein, one of skill in the art would recognize theclinically relevant measurement of visual function and/or retinalanatomy that could be used to treat the given ocular disease.

When the therapeutic agents of the present invention are administeredtogether with another agent, the two can be administered sequentially ineither order or simultaneously. In some aspects, an antibody of thepresent invention is administered to a subject who is also receivingtherapy with a second agent (e.g., Lucentis®). In other aspects, thebinding molecule is administered in conjunction with surgicaltreatments.

Suitable agents for combination treatment with Epo binding antibodiesinclude agents known in the art that are able to modulate the activitiesof VEGF, VEGF receptors, other receptor tyrosine kinase inhibitors, orother entities that modulate HIF-1 mediated pathways. Other agents havebeen reported to inhibit these pathways include ranibizumab,bevicizumab, pegaptanib, aflibercept, pazopanib, sorafinib, sunitinib,and rapamycin. Combination treatments with anti-inflammatory agents suchas corticosteroids, NSAIDS, and TNF-α inhibitors could also bebeneficial in the treatment of retinal vascular disease and macularedema, for example, diabetic retinopathy and DME.

A combination therapy regimen may be additive, or it may producesynergistic results (e.g., reductions in retinopathy severity more thanexpected for the combined use of the two agents). In some embodiments,the present invention provide a combination therapy for preventingand/or treating retinal vascular diseases and macular edema,specifically, diabetic retinopathy, including DME and/or PDR asdescribed above with an Epo binding antibody of the invention and ananti-angiogenic, such as anti-VEGF agent.

Pharmaceutical Compositions

The invention provides pharmaceutical compositions comprising theEpo-binding antibodies (intact or binding fragments) formulated togetherwith a pharmaceutically acceptable carrier. The compositions canadditionally contain one or more other therapeutic agents that aresuitable for treating or preventing, for example, diabetic retinopathy.Pharmaceutically acceptable carriers enhance or stabilize thecomposition, or can be used to facilitate preparation of thecomposition. Pharmaceutically acceptable carriers include solvents,dispersion media, coatings, antibacterial and antifungal agents,isotonic and absorption delaying agents, and the like that arephysiologically compatible.

A pharmaceutical composition of the present invention can beadministered by a variety of methods known in the art. The route and/ormode of administration vary depending upon the desired results. It ispreferred that administration be intravitreal, intravenous,intramuscular, intraperitoneal, or subcutaneous, or administeredproximal to the site of the target. The pharmaceutically acceptablecarrier should be suitable for intravitreal, intravenous, intramuscular,subcutaneous, parenteral, spinal or epidermal administration (e.g., byinjection or infusion). Depending on the route of administration, theactive compound, i.e., antibody, bispecific and multispecific molecule,may be coated in a material to protect the compound from the action ofacids and other natural conditions that may inactivate the compound.

The composition should be sterile and fluid. Proper fluidity can bemaintained, for example, by use of coating such as lecithin, bymaintenance of required particle size in the case of dispersion and byuse of surfactants. In many cases, it is preferable to include isotonicagents, for example, sugars, polyalcohols such as mannitol or sorbitol,and sodium chloride in the composition. Long-term absorption of theinjectable compositions can be brought about by including in thecomposition an agent which delays absorption, for example, aluminummonostearate or gelatin.

Pharmaceutical compositions of the invention can be prepared inaccordance with methods well known and routinely practiced in the art.See, e.g., Remington: The Science and Practice of Pharmacy, MackPublishing Co., 20th ed., 2000; and Sustained and Controlled ReleaseDrug Delivery Systems, J. R. Robinson, ed., Marcel Dekker, Inc., NewYork, 1978. Pharmaceutical compositions are preferably manufacturedunder GMP conditions. Typically, a therapeutically effective dose orefficacious dose of the Epo-binding antibody is employed in thepharmaceutical compositions of the invention. The Epo-binding antibodiesare formulated into pharmaceutically acceptable dosage forms byconventional methods known to those of skill in the art. Dosage regimensare adjusted to provide the optimum desired response (e.g., atherapeutic response). For example, a single bolus may be administered,several divided doses may be administered over time or the dose may beproportionally reduced or increased as indicated by the exigencies ofthe therapeutic situation. It is especially advantageous to formulateparenteral compositions in dosage unit form for ease of administrationand uniformity of dosage. Dosage unit form as used herein refers tophysically discrete units suited as unitary dosages for the subjects tobe treated; each unit contains a predetermined quantity of activecompound calculated to produce the desired therapeutic effect inassociation with the required pharmaceutical carrier.

Actual dosage levels of the active ingredients in the pharmaceuticalcompositions of the present invention can be varied so as to obtain anamount of the active ingredient which is effective to achieve thedesired therapeutic response for a particular patient, composition, andmode of administration, without being toxic to the patient. The selecteddosage level depends upon a variety of pharmacokinetic factors includingthe activity of the particular compositions of the present inventionemployed, or the ester, salt or amide thereof, the route ofadministration, the time of administration, the rate of excretion of theparticular compound being employed, the duration of the treatment, otherdrugs, compounds and/or materials used in combination with theparticular compositions employed, the age, sex, weight, condition,general health and prior medical history of the patient being treated,and like factors.

A physician or veterinarian can start doses of the antibodies of theinvention employed in the pharmaceutical composition at levels lowerthan that required to achieve the desired therapeutic effect andgradually increase the dosage until the desired effect is achieved. Ingeneral, effective doses of the compositions of the present invention,for the treatment of a retinal vascular disease described herein varydepending upon many different factors, including means ofadministration, target site, physiological state of the patient, whetherthe patient is human or an animal, other medications administered, andwhether treatment is prophylactic or therapeutic. Treatment dosages needto be titrated to optimize safety and efficacy. For systemicadministration with an antibody, the dosage ranges from about 0.0001 to100 mg/kg, and more usually 0.01 to 15 mg/kg, of the host body weight.For intravitreal administration with an antibody, the dosage may rangefrom 0.1 mg/eye to 10 mg/eye. More specifically, the dose may range from1 mg/eye to 9 mg/eye, 2 mg/eye to 8 mg/eye, 3 mg/eye to 7 mg/eye, 4mg/eye to 6 mg/eye, or 4.5 mg/eye to 5.5 mg/eye. In certain instancesthe does may be 0.1 mg/eye, 0.2 mg/eye, 0.3 mg/eye, 0.4 mg/eye, 0.5mg/eye, 0.6 mg/eye, 0.7 mg/eye, 0.8 mg/eye, 0.9 mg/eye, 1 mg/eye, 2mg/eye, 3 mg/eye, 4 mg/eye, 5 mg/eye, 6 mg/eye, 7 mg/eye, 8 mg/eye, 9mg/eye, or 10 mg/eye. An exemplary treatment regime entails systemicadministration once per every two weeks or once a month or once every 3to 6 months. An exemplary treatment regime entails systemicadministration once per every two weeks or once a month or once every 3to 6 months, or as needed (PRN).

Antibody is usually administered on multiple occasions. Intervalsbetween single dosages can be weekly, monthly or yearly. Intervals canalso be irregular as indicated by measuring blood levels of Epo-bindingantibody in the patient. In addition alternative dosing intervals can bedetermined by a physician and administered monthly or as necessary to beefficacious. Efficacy is based on lesion growth, rate of Lucentis®rescue, retinal thickness as determined by Optical Coherence Tomography(OCT), and visual acuity. In some methods of systemic administration,dosage is adjusted to achieve a plasma antibody concentration of 1-1000μg/ml and in some methods 25-500 μg/ml. Alternatively, antibody can beadministered as a sustained release formulation, in which case lessfrequent administration is required. Dosage and frequency vary dependingon the half-life of the antibody in the patient. In general, humanizedantibodies show longer half-life than that of chimeric antibodies andnonhuman antibodies. The dosage and frequency of administration can varydepending on whether the treatment is prophylactic or therapeutic. Inprophylactic applications, a relatively low dosage is administered atrelatively infrequent intervals over a long period of time. Somepatients continue to receive treatment for the rest of their lives. Intherapeutic applications, a relatively high dosage at relatively shortintervals is sometimes required until progression of the disease isreduced or terminated, and preferably until the patient shows partial orcomplete amelioration of symptoms of disease. Thereafter, the patientcan be administered a prophylactic regime.

EXAMPLES

The following examples are provided to further illustrate the inventionbut not to limit its scope. Other variants of the invention will bereadily apparent to one of ordinary skill in the art and are encompassedby the appended claims.

Example 1 Generation of Affinity Matured Epo Antibodies

A fully human phage display library was used to generate the Epo bindingantibodies described herein.

Biotinylated and non-biotinylated human and cynomolgus Epo were used insolution and solid phase pannings. Standard panning were performed aswell as RapMAT approaches (Prassler et al., (2009) Immunotherapy1(4):571-583). Following secondary screening and RapMAT panning, cloneswere selected for sequence analysis and a set of 8 antibodies wereselected for conversion to a FabCys format, germlining, pl optimizationand removal of deamidation sites. FabCys generation was accomplishedwith a proprietary RapCLONE®method. RapCLONE® was performed as atwo-step method for convenient and efficient conversion of a largeamount of Fab clones into the IgG and FabCys format. In a first cloningstep, a eukaryotic expression cassette was introduced into theexpression vectors pMORPH®x11 (for HuCAL PLATINUM®) via BsiWI/Mfel (forκ pools) or HpaI/MfeI (for λ pools) digestion and subsequent ligation.This was followed by a second cloning step, in which the Fab poolscontaining the expression cassette were digested using EcoRV/BlpI (κ andλ pools) and subsequently cloned into the pMorph®4_IgG1f orpMorph®4_h_FabCys acceptor vector for expression in mammalian cells. Forthis project, RapCLONE® was applied only on unique, sequenced andcharacterized Fab. Therefore all clones were recovered after RapCLONE®.

Low pls (<8.2) are generally associated with poor biophysical propertiesincluding stability and aggregation. 8 final candidates (HCDR3 uniqueclones) were selected for germlining, pl optimization and removal ofde-amidation sites leading to a total of 12 germlined variants. 12VL-genes were synthesized (two for 11317, 11324, 11331 and 11345) andone VH (11324). Possibly due to early de-selection of candidates withPTMs, only 11317 (VL), 11332 (VL) and 11380 (VH) contained de-amidationsites that were removed with the germlining. Germlining was in generaldone to the closest germline. To increase the pl, the lambda germline 3hwas chosen for 6 of the candidates instead of or in addition to theclosest germline 3r. Additionally lambda 3j variants were constructedfor three candidates to minimize risk (11317, 11331 and 11345).

Initial PTM- Final Final pl of Antibody modifications* plmodifications** FabCys FabCys 11317 3j, S96T NA NVS4 9.4 11319 3h Q105RNVS1 8.3 11331 3h Q1E NVS2 8.8 11380 3h Q105R, S33T NVS3 8.3 NA, Notapplicable *All PTM-modification occured in VL, **pl modificationsoccured in VH

As mentioned above, the pl of a protein is a key determinant of theoverall biophysical properties of a molecule. The anti-Epo Fabsidentified from the phage display library had pls lower than 8.2. Toimprove the manufacturing properties, the antibodies were specificallyengineered to increase their pl and improve their drug-like properties.Increasing the pl of the anti-Epo Fabs improved their solubility,enabling the Fabs to be formulated at higher concentrations (>100mg/ml). Formulation of the Fabs at high concentrations (e.g. >100 mg/ml)offers the advantage of being able to administer higher doses of theFabs into eyes of patients via intravitreal injections, which in turnmay enable reduced dosing frequency, a significant advantage fortreatment of chronic ocular diseases including, but not limited to wetAMD and diabetic retinopathy.

The resulting Fabs are shown in Table 1 (NVS1, NVS2, NVS3, and NVS4).

Example 2 Characterization of Optimized Antibodies

The following example describes methods that may be used to measureantibody affinity. These and other methods of measuring binding affinityare known in the art.

Affinity Determination

Antibody affinity for Epo was measured by surface plasmon resonance(SPR) using a Biacore® T200 (Biacore) and solution equilibrium titration(SET). Explanations of each technology and corresponding mean resultsfor Epo binding are described below. Modelling assumptions take intoaccount concentrations of Epo in the system, kinetics of Epobiosynthesis and half-life, as well as the desired dosing schedule, andsuggest that a Fab with an affinity of less than 50 pM for Epo issufficient to lower levels of free Epo.

Biacore Determination

The kinetics of an interaction, i.e. the rates of complex formation(k_(a)) and dissociation (k_(d)), can be determined from the informationin a sensorgram. If binding occurs as sample passes over a preparedsensor surface, the response in the sensorgram increases. If equilibriumis reached a constant signal will be seen. Replacing sample with buffercauses the bound molecules to dissociate and the response decreases.Biacore evaluation software generates the values of k_(a) and k_(d) byfitting the data to interaction models.

Three flow cells were utilized for the method run. Flow cell 1 (fc1)served as the reference, where no Epo Fab was captured, to assess fornon-specific binding of the Epo to the antibody coated chip surface.Both capture and binding steps were carried out on flow cells 2-4.

Capture step: In order to achieve an Rmax of 20, the capture level ofanti-hu Fab on fc2-4 was approximately 50 RL. Anti-hu Fab at aconcentration of 1 ug/ul, flowed over Fc2-4 at a flow rate of 10 μl/min.

The calculations for the relative Rmax is as follows:

Fabs: R _(max) =R _(L)*(MW _(analyte) /MW _(ligand))*stoichiometry20=RL*(21.4/50)*1=50 RL

The analyte started at concentrations of 20 nM and included 8 1:2dilutions with a duplicate at 2.5 nM for the long and shortdissociation. The analyte was run at a flow rate of 60 μl/min for 240seconds. Dissociation times were set at 4000 seconds and 600 seconds.Dissociation time was set at 4000 seconds for 10 nM, 2.5 nM and 0.3125nM analyte concentrations for NVS2 and NVS4. After the sample injection,there was a wash step with the regeneration buffer.

Regeneration was performed at the end of each cycle on all flow cells.Regeneration condition for this method was 1% Phosphoric acid with 10%sodium Hydroxide at 60 μl/min for 100 seconds.

All other running conditions were carried out at 25° C. in 1× HBS-EP+buffer (Biacore cat #BR-1006-69). The resulting signals were adjusted bydouble referencing, thus subtracting the refraction index values fromthe reference flow cell and the binding step with no analyte. Data wascollected at 10 Hz and analyzed using the Biacore® T100 EvaluationSoftware Version 1.1 (GE Healthcare). This program uses a global fittinganalysis method for the determination of rate and affinity constants foreach interaction.

The results of the Biacore binding kinetics determination are shown inTable 2. As shown the antibodies described herein exhibited highaffinity binding to human Epo, with K_(D) values typically less than orequal to 40 pM.

TABLE 2 Affinity Binding of Epo Antibodies (Biacore) K_(D) (pM) Epo NVS2NVS3 NVS4 NVS1* Human 34.2 37 27.1 11 Human-darbapoetin 23.5 ND 18.1 NDCyno 78.7 49 76.0 31 Mouse 44.9 1 30.5 22 Rat 56.6 38 34.4 41 Rabbit5160 674 ND 661 ND: not determined *Data shown for NVS1 is singledatapoint

SET Determination

In contrast to kinetic assays using sensor surfaces, such as SPR, SET isa method which determines affinities in solution. It is an equilibriummeasurement that does not deliver kinetic data.

In SET, a constant amount of antibody is incubated with differentconcentrations of antigen until equilibrium is reached. Theconcentration of free antibody in the equilibrated solution isdetermined by applying the solution on an antigen coated MSD™ plate(Meso Scale Discovery™) followed by incubation with an ECL-labeledsecondary antibody and measurement of signal intensity. At low antigenconcentrations, a strong signal is achieved (high concentration of freeantibody which binds to the antigen on the plate) whereas for highantigen concentration, the antibody is completely antigen-captured,resulting in a low signal. If a sufficient number of antigenconcentrations in a matching range are available, the titration curveallows for a reasonable determination of the affinity, using theappropriate fit model. For a complete titration, antigen concentrationsof at least 10-fold higher than the anticipated K_(D) have to beapplied. The constant concentration of antibody applied in the assayshould be in the range of, or below, the K_(D) (Table 3).

For K_(D) determination by SET, monomer fractions of antibody proteinwere used (at least 90% monomer content, analyzed by analytical SEC;Superdex75 (Amersham Pharmacia) for Fab, or Tosoh G3000SWXL (TOSOHBIOSCIENCE) for IgG, respectively).

Affinity determination in solution was basically performed as describedin the literature (Friguet et al. 305-19). In order to improve thesensitivity and accuracy of the SET method, it was transferred fromclassical ELISA to ECL based technology (Haenel et al., 2005).

Epo antibodies were diluted to a fixed concentration in incubationbuffer (PBS with 2% BSA (Sigma cat #A4503) and 1% Tween20 and 1%Triton-X (Sigma cat #234729)), and added to a serial dilution (1:5) ofEpo in incubation buffer.

Final Highest Concentration of Epo:

Human, Hu-darbapoetin, cynomolgus, mouse, rat=10 nM

Rabbit=100 nM

Final Concentrations of Fabs:

NVS2: 2 pM, except Rabbit=30 pM

NVS3: 2 pM, except Rabbit=5 pM

NVS4: 2 pM, except Rabbit=10 nM

NVS1: 2 pM

Samples were allowed to reach equilibrium by incubation at RT overnight.

Streptavidin-coated standard MSD plates (Meso-Scale Discovery, 384-well:MSD cat #L11 SA) were blocked with 25 μl incubation buffer at RT for 1hr. Plates were washed 3× in TBST buffer (25 mM TBS with 0.05% Tween20),and 0.1 μg/ml of biotinylated-Epo was added in 25 μl incubation bufferand incubated at RT for 1 hr. Plates were washed 3× in TBST buffer.Samples containing Fabs and Epo titration were added to the plate (25μl), and incubated at RT for 15 min. Plates were washed 3× in TBSTbuffer. 25 μl detection antibody was added (Anti-Human (Goat) Sulfo-TAG,1:1000 in incubation buffer, MSD cat #R32AJ-1), and incubated at RT for60 min. Plates were washed 3× in wash buffer, and 50 μl of 1× MSD Readbuffer T was added (with surfactant, MSD cat #R92TC-1). Plates were readon a MSD Spector Imager 6000.

Three experiments were performed on separate days, each data point intriplicate.

Data was analyzed using GraphPad Prism software v4, with background (anaverage of wells containing no Fab) subtracted from each value. X-axisvalues (concentration of Epo in solution) were transformed into log 10×.

KD values (KD) were fitted from the following model:

Y=(Top−((Top/(2×Fab))×((((10{circumflex over( )}x)+Fab)+KD)−((((((10{circumflex over( )}x)+Fab)+KD)×(((10{circumflex over( )}x)+Fab)+KD))−((4×(10{circumflex over ( )}x))×Fab)){circumflex over( )}0.5))))

Top=signal at antigen concentration=0

x=concentration of Epo in solution

Fab=constraint for Fab concentration was set to 1 pM

Affinities of Epo Fabs were determined using the SET assay and resultingK_(D) values ([pM] concentrations) are summarized in Table 3. NVS2 boundhuman, human-darbepeotin and cynomolgus Epo with a K_(D) less than 10pM. NVS2 also bound mouse Epo with a K_(D) less than 50 pM and rat Epowith a K_(D) less than 20 pM. NVS3 bound human, human-darbepeotin,cynomolgus, mouse and rat Epo with a K_(D) less than 5 pM. NVS4 boundhuman, human-darbepoetin, cynomolgus, mouse and rat Epo with a K_(D)less than 10 pM.

TABLE 3 Affinity Binding of Epo Antibodies (SET) K_(D) (pM) Epo NVS2NVS3 NVS4 NVS1* Human 5.4 0.9 2.5 1.2 Darbepoietin 3.7 0.5 1.3 ND Cyno7.3 0.8 7.3 4.4 Mouse 37.0 2.5 7.8 16.1 Rat 12.7 1.2 12.7 5.4 Rabbit3864.7 39.9 28670 ND ND: not determined *Data shown for NVS1 is singledatapoint

Example 3 Inhibition of Epo Induced Cell Proliferation

Cells which are dependent on erythropoietin for growth and survival canbe utilized to measure the potency of anti-Epo therapeutics by means ofEpo-dependent proliferation inhibition (Chiba et al., 1991).

Example 3a Ba/F3-EpoR Cell Proliferation Assay

This assay demonstrates the ability of Epo antibodies to inhibit Epoinduced cell proliferation in mouse Ba/F3 cells expressing the Eporeceptor (Ba/F3-EpoR cells). Ba/F3 cells are IL-3 dependent for growthand survival and have been shown to grow in an IL-3 independent mannerupon transformation with various oncogenic tyrosine kinases. Upon stabletransfection with EpoR, Ba/F3-EpoR cells became IL-3 independent. Themammalian expression plasmid pcDNA3.1 carrying human EpoR wastransfected into Ba/F3 cells using the Amaxa nucleofection system(catalogue number VCA-1003, Amaxa GmbH) according to the manufacturer'sinstructions using the Nucleofector device (Amaxa, Nucleofactor™ II).

Materials Materials Description Source Catalog # 384-well plate Matrix384-well ThermoScientific 50823639 microplate 384-well plateuClear-Plate Black, Greiner Bio-One 7881091 384 well TC w/Lid RPMI 1640Invitrogen 11875 FBS Hyclone SH30071.03 Pen/Strep Invitrogen 15140Hygromycin B Invitrogen 10687010 Epo Genway 10-663-45072 DarbepoietinSandoz CAS #: 209810-58-2 Ba/F3-EpoR cells Described herein Cell TiterBlue Promega G8081

Cell Maintenance

Growth Medium: RPMI1640/10% FBS/1% Pen-Strep/100 μg/ml Hygromycin B/1U/ml Epo

Assay Medium: RPMI1640/10% FBS/1% Pen-Strep/100 μg/ml Hygromycin B

Ba/F3-EpoR cells were maintained in growth medium(RPM11640/10%FBS/1%Pen-Strep/100 μg/ml Hygromycin B/1 U/ml Epo). Cellswere split at ˜1e6 cells/ml (every 3-4 days) down to 0.4-0.6e5 cells/ml.

Epo Induced Cell Proliferation Assay

-   -   1. A day before the experiment, Ba/F3-EpoR cells were prepared        by centrifugation to remove growth medium, following which the        cells were resuspended in assay medium (RPMI1640/10% FBS/1%        Pen-Strep/100 μg/mL Hygromycin B) which does not contain Epo.    -   2. On the day of experiment, cells were washed 2-3 times in        assay medium (centrifuge 1000 rpm, 5 min) and resuspended in        assay medium at 1.25×10⁵ cells/ml.    -   3. 2500 cells were added to each assay well in a 384-well black        plate (clear bottom, TC treated).    -   4. Epo was serially diluted in a 384-well microplate with assay        media such that the final concentration of Epo was two-fold        higher than desired final concentration.    -   5. 20 μl of serially diluted Epo (in triplicate) was added in        triplicate to sample wells containing Ba/F3-EpoR cells of        384-well black plate.    -   6. The plate was spun in a centrifuge at 1000 rpm for 30-60        seconds and incubated for 48 hrs at 37° C., 5% CO₂.    -   7. Four hours prior to endpoint, 8 μl Cell Titer Blue was added        to all wells and re-incubated at 37° C., 5% CO₂.    -   8. Four hours later, the plate was read on a Beckman Coulter        Paradigm with Paradigm Multimode SW, or comparable scanner.    -   9. Epo stimulated proliferation of Ba/F3-EpoR cells 4-fold over        baseline. Epo stimulated Ba/F3-EpoR with an average EC₅₀ of 11.2        pM and range of 10 pM and 26 pM.    -   10. Anti-Epo antibodies were serially diluted in triplicate in a        384-well microplate containing 4 ng/ml Epo in assay medium and        incubated for 30 minutes at room temperature.    -   11. 20 μl/well of the above Epo/anti-Epo antibody mixture was        added to the 384-well black walled plate previously seeded with        2500 BaF3/EpoR cells per well.    -   12. Post-incubation plates were processed as outlined in steps        7-9 above

Results

Epo antibodies inhibited Ba/F3-EpoR cells proliferation in the presenceof 1 ng/ml Epo after 48 hrs. Antibodies inhibited Ba/F3-EpoR cellproliferation with an IC₅₀ less than or equal to 350 pM.

TABLE 4 IC₅₀ (pM) Assay NVS2 NVS3 NVS4 NVS1 Epo26 Ba/F3 112.0 76.3 173.1338 590 Assay

Example 3b F36E Cell Proliferation Assay

F36E cells are highly dependent on Epo for proliferation. Stimulationwith Epo using the methods described above typically results in agreater then 6-fold signal over baseline. The EC50 of this curve is 7pM.

Protocol for Neutralization of Epo Induced F36E Cell Proliferation Assay

A proliferation assay using the F36E cell line, an Epo-dependentlymphocyte-like immortalized cell line derived from a parental bonemarrow cell line, was used for screening anti-Epo therapeutic antibodiesand to select candidates for development.

Materials

Materials/reagents Source Catalog # 384 well polystyrene cell cultureGreiner Bio One 781091 microplates, black 384 well polypropylenemicroplate Greiner Bio One 781280 without lid RPMI 1640 Invitrogen 11875FBS Hyclon SH30071.03 Pen/Strep lnvitrogen 15140 Darbepoietin Sandoz CAS#: 209810-58-2 F36E cells Riken Cell Bank RCD0776 Cell Titer BluePromega G8081 Epo26 anti-human Epo monoclonal Stem Cell Tech 01350antibody

Cell Maintenance

Darbepoietin, a recombinant hyperglycosylated human Epo, was used forcell maintenance and proliferation assays described herein. Darbepoietinstimulates proliferation in F36E cells with a comparable EC50 torecombinant human Epo (63.2 pg/ml darbepoietin and 81.25 pg/mlerythropoietin; see LU-15432, pg. 44). F36E cells were maintained ingrowth media (RPM11640/5% FBS/1% Pen-Strep/5.2 U/ml dEpo) at minimumdensity 0.25e6 cells per ml to maximum density 1.0e6 cells per ml up to10 passages.

Epo Induced Proliferation Assay Protocol

-   -   1. Epo was diluted in assay media (RPM11640/5% FBS/1% Pen-Strep)        to 4 ng/ml, 4×-fold desired final concentration.    -   2. Anti-Epo antibody was diluted in assay media to 200 nM, 4×        final concentration, and this concentration was serially diluted        in assay media for six points. Dilution was repeated for a        positive reference antibody (e.g.: Epo26) and a negative        reference antibody (e.g.: anti-chicken lysozyme monoclonal        antibody).    -   3. 7.5 ul diluted dEpo and 7.5 ul anti-Epo antibody serial        dilutions were mixed in 384-well polypropylene microplate, in        triplicate, and incubated at room temperature for 30 minutes.    -   4. F36E cells (2e6 per 384-well plate) were pelleted, growth        media was aspirated and cells were washed once in assay media        (centrifuge 1200 rpm, 5 min), then resuspended in assay media to        3.33e5 cells/ml.    -   5. 15 μl/well cells (5,000 cells/well) were added to all wells        in 384-well polystyrene cell culture plate.    -   6. 15 ul antibody-Epo mixture was added to cells.    -   7. Incubated 68 hrs at 37° C., 5% CO2.    -   8. 8 μl Cell Titer Blue was added per well and incubated at 37°        C., 5% CO2 for 4 hours.    -   9. Fluorescence was meadured at 560(20)Ex/590(10)Em on a        Fluoroskan Ascent Microplate Fluorometer or comparable scanner.    -   10. The average RFU+/−standard deviation vs. nM antibody was        plotted and IC50 determined by non-linear regression curve fit        in Graph Pad Prizm software.

Results

Anti-Epo antibodies inhibited F36E cell proliferation with an IC₅₀ lessthan or equal to 200 pM.

TABLE 5 IC₅₀ (pM) Assay NVS2 NVS3 NVS4 NVS1 Epo26 F36E Assay 144.1 88.7182.7 175 590

Example 4 Epitope Binding

Synthetic Peptide & Peptide Trunctation Studies

Synthetic peptides corresponding to structural domains of human Epo(hEpo), domain truncations of hEpo, or chimeric molecules containingportions of hEpo and human thrombopoietin (TPO) were synthesized orexpressed recombinantly. Positive binding to the synthetic peptidesindicated that residues contained in that domain of Epo were involved inbinding to the anti-Epo antibody. For the truncated proteins, loss ofbinding indicated the involvement of the truncated portion in binding tothe anti-Epo antibody. However, the loss of binding did not preclude thepossibility that the truncation altered the structure of the remainingprotein significantly so as to affect binding to the anti-Epoantibodies. The human Epo-human TPO chimeras enabled maintenance ofstructure while still allowing epitope mapping. Loss of binding to avariant that contained a portion of hTPO indicated that the homologousregion in hEpo was important for binding to the anti-Epo antibody.

Peptide Epitope Mapping of Anti-Erythropoietin Antibodies

The following six peptides (Table 6), corresponding to the helices oferythropoietin were synthesized.

TABLE 6 Peptide Sequence EPO domain 1 SEQ ID NO: 86 Helix ARLICDSRVLERYLLEAKEAENITTG 2 SEQ ID NO: 89 Loop A-B ITVPDTKVNFYAWKRM 3SEQ ID NO: 87 Helix B EVGQQAVEVWQGLALLSEAVLRGQALLVNS 4 SEQ ID NO: 90Helix C EPLQLHVDKAVSGLRSLTTLLRALGAQKEA ISPPD 5 SEQ ID NO: 91 Helix CDKAVSGLRSLTTLLRAL 6 SEQ ID NO: 88 Helix D TFRKLFRVYSNFLRGKLKLYTGEACR

Assay Set Up

-   -   1. 25 ul of peptide in PBS (5 ug/ml) was coated on 384 well MSD        standard plate (Mesoscale Discovery, Cat. No. L21XA-4)        overnight.    -   2. The plate was blocked with 90 ul of        PBS+5%BSA/0.1%Tween-20/0.1% TritonX-100 for 4 hours.    -   3. 500 nM Morphosys Epo Fab in diluents of        PBS+2%BSA/0.1%Tween-20/0.1% TritonX-100 was added to plate and        incubated for 1 hour.    -   4. The plate was washed and incubated with Sulfo-tag anti-human        IgG (Meso Scale Discovery, Cat. No. R32AJ-1) for Epo Fabs or        species appropriate for reference proteins/antibodies (1 hr)    -   5. Plate was washed and MSD Read Solution (Meso Scale Discovery,        Cat. R92TC-1) was added.    -   6. Read plate

Epitope Mapping of Anti-Erythropoietin Antibodies with TruncatedVariants of Erythropoietin

Epo Variant 1: Helix A

Epo Variant 2: Helix A, Loop A-B

Epo Variant 3: Helix A, Loop A-B, Helix B

Epo Variant 4: Helix A, Loop A-B, Helix B, Loop B-C, Helix C

Epo Variant 5: Full length erythropoietin

Assay Set Up

-   -   1. Plate was coated with biotinylated HEK293 expressed Epo        variants on standard streptavidin 384 well plate plate        (Mesoscale Discovery, Cat. No. L21SA-1) overnight at 4° C.    -   2. The plate was blocked with 90 ul of PBS+5% BSA/0.1%        Tween-20/0.1% TritonX-100 for 4 hours.    -   3. The place was washed and 500 nM Morphosys Epo Fab was added        to the plate and incubated for 1 hour    -   4. The plate was washed and incubated with Sulfo-tag anti-human        IgG (Meso Scale Discovery, Cat. No. R32AJ-1) for Epo Fabs or        species appropriate for reference proteins/antibodies (1 hr)    -   5. The plate was washed and MSD Read Solution (Meso Scale        Discovery, Cat. R92TC-1) was added.    -   6. Read plate

Epitope Mapping of Anti-Erythropoietin Antibodies withEpo/Thrombopoietin (Tpo) and Rabbit/Human Epo Chimerics

Epo/Tpo Chimerics

Epo/Tpo Variant 1: Human Epo with Tpo Helix A

Epo/Tpo Variant 2: Human Epo with Tpo Loop A-B

Epo/Tpo Variant 3: Human Epo with Tpo Helix B

Epo/Tpo Variant 4: Human Epo with Tpo Helix C

Epo/Tpo Variant 5: Human Epo with Tpo Helix D

Rabbit/Human Epo Chimerics

Rb/Hu Epo Variant 1: Rabbit Epo with Human Helix A

Rb/Hu Epo Variant 2: Rabbit Epo with Human Loop A-B

Rb/Hu Epo Variant 3: Rabbit Epo with Human Helix B

Rb/Hu Epo Variant 4: Rabbit Epo with Human Loop B-C and Helix C

Rb/Hu Epo Variant 5: Rabbit Epo with Human Loop C-D

Rb/Hu Epo Variant 6: Rabbit Epo with Human Helix D

Assay Set Up

1. 25 ul of Epo chimerics in PBS (2 ug/ml) were coated on a 384 well MSDstandard plate (Mesoscale Discovery, Cat. No. L21XA-4) overnight at 4°C.

2. The plate was blocked with 90 ul of PBS+5% BSA/0.1% Tween-20/0.1%TritonX-100 for 4 hours.

3. 500 nM Morphosys Epo Fab in diluents of PBS+2% BSA/0.1% Tween-20/0.1%TritonX-100 was added to plate and incubated for 1 hour.

4. The plate was washed and incubated with Sulfo-tag anti-human IgG(Meso Scale Discovery, Cat. No. R32AJ-1) for Epo Fabs or speciesappropriate for reference proteins/antibodies (1 hr)

5. The plate was washed and MSD Read Solution (Meso Scale Discovery,Cat. R92TC-1) was added.

6. Read plate

General Protocol

Standard capture 384-well MSD plates (Meso Scale Discovery) were coatedwith peptide (5 ug/ml in PBS, New England Peptide LLC) or Epo chimerics(2 ug/ml in PBS) and incubated overnight at 4° C. Biotinylated truncatedEpo variants (2 ug/ml in PBS) were coated on standard streptavidincapture 384-well MSD plates overnight. After washing the plates 1× withTBST (Thermo Scientific, Cat. No. Cat. No. 28360), the plates wereblocked in diluent (PBS, 5% BSA, 0.1% Tween-20, 0.1% TritonX-100) for 4hours at room temperature. Plates were washed 3× in TBST. Five hundrednanomolar of anti-erythropoietin fabs were added to the peptide/Epovariants precoated MSD plates for 1 hour. Plates were washed 3× in TBSTand anti-Human IgG-Sulfotag (1 ug/ml, Meso Scale Discovery, Cat. No.R32AJ-1) was added and incubated for 60 minutes. Plates were washed 3×in TBST and 1× Read Buffer T (Meso Scale Discovery, Cat. No. R92TC-1)was added. The plates were read on a MSD Spector Imager 6000 and datawas analyzed using GraphPad Prism software v4.

Results:

Results indicated that the antibodies minimally bound to the followingdomains (Table 7). No antibodies bound to Helix C.

TABLE 7 Helix A Loop A-B Helix D NVS1 ++ + NVS2 ++ + NVS3 + + ++ NVS4 ++(++) Dominant epitope; (+) observed bindingCrystal Structure of Antibodies in Complex with Epo

Glycosylated, recombinant human Erythropoeitin (Epo) was received fromLEK Pharmaceuticals, Inc.

Epo was de-glycosylated using Protein De-glycosylation Mix (New EnglandBiolabs, cat #P6039S). 30 mg of hEpo was combined with 1 ml of ProteinDeglycosylation Mix and incubated at 37° C. for 1 hour at which pointde-glycosylation was incomplete as determined by SDS-PAGE. An additional0.5 ml of Protein De-glycosylation Mix was then added to Epo andincubated for a further 1 hour at 37° C. Gel analysis showed nearcomplete deglycosylation of Epo. This protein was then further purifiedusing a 120 ml Superdex75 column (GE Healthcare, cat #28-9893-33)equilibrated in 25 mM HEPES pH 7.5, 150 mM NaCl. Elution fractionscontaining the highest level of de-glycoslation of hEpo were pooled.Protein complexes were formed by combining 5 mg of de-glycosylated Epowith 7 mg of NVS3, followed by incubation on ice for 1 hour. The proteincomplex mix was then concentrated and applied to a 120 ml Superdex 75,equilibrated in 25 mM HEPES pH 7.5, 150 mM NaCl. Fractions containingSDS-gel evaluated stoichiometric ratios of Epo:NVS3 were pooled andconcentrated to 19 mg/ml (concentration estimated by LCUV) (PRONOVA#27SN). Crystallization screens were set up using this concentratedEpo:NVS3 complex. Crystals were grown by the technique of sitting-dropvapor diffusion, with the drops containing equal volumes of protein andreservoir solution. Crystals formed at 4° C. with the followingreservoir condition: 0.1M Hepes pH 7.0, 12% PEG3350, 50 mM zinc acetatedehydrate. Crystals were frozen using the following cryoprotectionsolution:0.1M Hepes pH 7.0, 15% PEG3350, 50 mM zinc acetate dehydrate,22% glycerol.

Epo:NVS3 complex crystal diffraction data were collected at beamline17-ID at the Advanced Photon Source (Argonne National Laboratory, USA).Data were processed and scaled at 2.6Å using autoPROC (Global Phasing,LTD) in space group C2 with cell dimensions a=125.57Å, b=150.15 Å,c=163.84Å, alpha=90°, beta=110.81°, gamma=90°. The Epo:NVS3 structurewas solved by molecular replacement using Phaser (McCoy et al., (2007)J. Appl. Cryst. 40:658-674). The Fab from 3H0T structure in the PDBdatabase (Berman 2000) was split into variable and constant domains, andthe human erythropoietin structure Syed et. al., Nature. 1998 Oct. 1;395(6701):511-6, PDB code 1 EER, were used as search models.

The final model, which contains 3 molecule of the Epo:NVS3 complex perasymmetric unit, was built in COOT (Emsley & Cowtan (2004) Acta Cryst.60:2126-2132) and refined to R and R_(free) values of 23.0% and 26.7%,respectively, with an rmsd of 0.010 Å and 1.34° for bond lengths andbond angles, respectively, using PHENIX (Adams et al., Acta Cryst. D66,213-221 (2010)).

The crystal structure of Epo:NVS3 was solved and refined to 2.6Å. Itrevealed an asymmetric unit composed of three Epo:NVS2 proteincomplexes, each composed of one Fab bound to one Epo protein. Two ofthese complexes form a zinc mediated dimer and the third exhibits higherb-factors and weaker density. Interactions from the Fab to Epo weremediated by the complementarity determining region (CDR) loops from boththe heavy and light chains of NVS3. Conformational changes of Epo whencompared to 1 EER were limited to loops distal from the Fab bindingepitope, with an RMSD of 0.5Å for all 144 aligned amino acids. The heavyand light chains of Fab NVS3 show typical immunoglobulin-like folds forthe domains.

The crystals structure of Epo:NVS3 was used to identify the Epo epitopeof the fragment antigen binding of NVS3. The interaction surface on Epowas formed primarily by residues comprising residue Ser⁹, Glu¹³,residues Thr⁴⁴ through Arg⁵³ and residues Asn¹⁴⁷ through Arg^(162.)These correspond to the secondary structure elements of Epo denoted asα-helix A, loop βA-αB and α-helix D. These residues formed thethree-dimensional surface that is recognized by NVS3. Interactionsincluded backbone interactions, solvent mediated interactions, anddirect side-chain interactions.

TABLE 8 Epo interacting residues to NVS3 Contact Exposed PercentageAmino Residue Area Area buried Acid number (A2 (A2) (%) Ser 9 11.7993.23 13 Glu 13 14.89 103.00 14 Thr 44 22.47 61.60 36 Lys 45 39.98172.59 23 Val 46 34.38 55.22 62 Asn 47 48.17 81.92 59 Phe 48 83.76129.76 65 Tyr 49 96.12 137.70 70 Ala 50 12.68 57.03 22 Trp 51 0.63 43.741 Lys 52 23.97 135.25 18 Arg 53 49.96 181.86 27 Asn 147 34.39 48.65 71Arg 150 73.32 140.37 52 Gly 151 18.97 24.63 77 Lys 154 73.59 127.20 58Leu 155 34.85 75.06 46 Gly 158 18.59 43.31 43 Glu 159 32.95 122.17 27Arg 162 36.72 185.91 20

Epo residues that contain atoms in contact with NVS3 are listed in Table9. Contact is defined to be within 5 Å of NVS3 to account for potentialwater mediated interactions.

TABLE 9 Protein Amino acid Sequence position* Epo Domain Epo S 9 Helix AEpo E 13 Helix A Epo T 44 Loop A-B Epo K 45 Loop A-B Epo V 46 Loop A-BEpo N 47 Loop A-B Epo F 48 Loop A-B Epo Y 49 Loop A-B Epo A 50 Loop A-BEpo W 51 Loop A-B Epo K 52 Loop A-B Epo R 53 Loop A-B Epo N 147 Helix DEpo R 150 Helix D Epo G 151 Helix D Epo K 154 Helix D Epo L 155 Helix DEpo G 158 Helix D Epo E 159 Helix D Epo R 162 Helix D *Sequence Positionrelative to SEQ ID NO: 81

Epo residues that contain atoms in contact with NVS2 are listed. Contactis defined to be within 5 Å of protein partner to account for potentialwater mediated interactions.

TABLE 10 Protein Amino acid Sequence position* Epo Domain Epo E 23 HelixA Epo D 43 Loop A-B Epo T 44 Loop A-B Epo K 45 Loop A-B Epo V 46 LoopA-B Epo N 47 Loop A-B Epo F 48 Loop A-B Epo Y 49 Loop A-B Epo A 50 LoopA-B Epo K 52 Loop A-B Epo R 53 Loop A-B Epo R 131 Helix D Epo R 143Helix D Epo N 147 Helix D Epo R 150 Helix D Epo G 151 Helix D Epo K 154Helix D Epo L 155 Helix D Epo E 159 Helix D Epo R 162 Helix D *SequencePosition relative to SEQ ID NO: 81

Example 5 In Vivo Model Example 5a Mouse Model of Ocular Edema

C57/B16 mice (Taconic) were sub-retinally injected with ssAAV2-EPO-eGFP(DR005) and ssAAV2-EGFP (TM003) (control). Mice were sacrificed threeweeks (21 days) post-injection. The retinas were flat-mounted and thevessel caliber was measured.

Methods:

Subretinal Injection of ssAA V2-EPO-eGFP and ssAA V2-eGFP

8-week old C57/B16 mice were divided into two groups (10 mice each, 20eyes/group) and sub-retinally injected with 1 μl ssAAV2 at 2×10⁹ DRP/μl.The first group (control) received sub-retinal ssAAV2-EPO (TM003), andthe second (experimental) ssAAV2-eGFP (DR005). The effect of mouse Epoon the retinal vascular changes was examined in retinal flat-mounts at21 days post injection.

The AAV (adeno-associated virus) tested were: ssAAV2-EPO-eGFP[(AAV2-CMV-mEPO-IRES-eGFP) from Gene Therapy Center Virus Vector CoreFacility, The University of North Carolina at Chapel Hill, Lot #AV3782]and ssAAV2-GFP [(AAV2-eGFP) from Gene Therapy Center Virus Vector CoreFacility, The University of North Carolina at Chapel Hill: Lot #AV3725].

Procedure:

-   -   AAV vectors were delivered via sub-retinal injection on both        eyes of the mice tested. All procedures described were performed        under aseptic conditions, using sterile reagents, syringes and        appropriate PPE.    -   1. The mice were immobilized, and their pupils dilated with a        drop of cyclopentolate (1%), followed by a drop of 2.5%        phenylephrine.    -   2. Next, the animal was anesthetized with Avertin (250 mg/kg)        i.p. The cornea was topically anesthetized with a drop of 0.5%        proparacaine.    -   3. After placing the animal under a surgical microscope, a        micro-scalpel was used to make a 0.5 mm nasal incision,        posterior to the limbus.    -   4. A blunt needle attached to a 10 μl Hamilton syringe was        tangentially inserted through the scleral incision toward the        temporal retina. The needle was advanced until resistance was        felt.    -   5. 1 μl of ssAAV2 vector (either ssAAV2-EPO-eGFP or ssAAV2-GFP,        both containing fluorescein diluted 1:50 to visualize delivery)        was slowly injected into the sub-retinal space.    -   6. The eye was examined under the surgical microscope. A        successful sub-retinal injection was confirmed by visualizing a        fluorescein containing retinal detachment.    -   7. The injection was scored depending on the degree of retinal        damage (visualized by hemorrhage size) and damage to the lens.    -   8. The animal was turned to the other side and the procedure was        repeated.    -   9. Antibiotic ointment was applied to both eyes after injection.

Retinal Dissection, Imaging and Quantification on Retinal Flatmount:

-   -   1. 0.1 ml Concavalin-A (Con-A) was injected (i.v., tail vein) 1        to 5 minutes before euthanasia (CO₂)    -   2. The eyes were enucleated and fixed in paraformaldehyde (4% in        PBS) for two hours. They were subsequently maintained at 4° C.        in PBS buffer for 1-3 days until dissection    -   3. The cornea and lens were removed, and the retina was        dissected from the posterior eye cup (retinal pigmented        epithelium/choroid)    -   4. Four radial incisions were made to the retina and        flat-mounted in Vectashield mounting media with the        photoreceptor layer face down.    -   5. Once mounted, the flat-mounts were centered on the central        retina (using the optic nerve head as a reference) and the Con-A        labeled retinal vessels were captured at 20× using the Zeiss        Imaging System (AxioVision)    -   6. The AxioVision software was used to measure the diameter of        central retinal vessels that are 200 μm away from optical nerve        head.    -   7. Data obtained was analyzed with GraphPad Prism.

Results and Conclusion:

Quantification of vessel diameter revealed that ssAAV2-EPO inducedsignificant (*p<0.001) vessel dilation in the central retina compared tossAAV2-GFP and naïve eyes (6 eyes) (FIG. 1). No significant differencewas found comparing ssAAV2-GFP vs. naïve group. Samples were analyzedusing a one-way ANOVA with Dunnet's post-test (C) Representativeflat-mounts for each group. Long-term delivery of Epo by AAV2-Epo-eGFPresulted in a statistically significant increase in venous caliber (FIG.1), a key hallmark of diabetic macular edema in humans. Accordingly, inone aspect, the invention relates to a method of decreasing venouscaliber in the eye by administering an anti-EPO antibody describedherein to a subject in a therapeutically effective amount.

Example 5b In Vivo Efficacy of Anti-Epo Antibodies

The in vivo activity, and therapeutic efficacy, of the anti-Epoantibodies described herein can be assessed in the mouse model of ocularedema described above.

In Vivo Challenge in the Mouse Model

C57B6 mice aged 8 weeks old are injected subretinally with one of thefollowing. Groups:

-   Group 1: AAV2-eGFP@titer 2×10⁹ DRP@titer, 1 ul/eye, n=20 eyes of 10    mice-   Group 2: AAV2-Epo-eGFP@titer 2×10⁹ DRP, 1 ul/eye, n=20 eyes of 10    mice-   Group 3: AAV2-Epo-eGFP@titer 2×10⁹, 1 ul/eye, +anti-Epo Fab, 100    ug/eye, 1 weekly, n=20 eyes of 10 mice

The effect of anti-Epo antibodies dosed appropriately are examined inthe mouse model by measuring vessel diameter 2 weeks post injection.

AAV-GFP (AAV2-eGFP) and AAV2-Epo-eGFP (AAV2-CMV-mEpo-1RES-eGFP) fromGene Therapy Center Virus Vector Core Facility, The University of NorthCarolina at Chapel Hill.

Intraocular injection of the anti-Epo antibodies will inhibit retinalvessel dilation anti-Epo antibodies to ameliorate the effects of Epo ondecrease blood flow and hypoxic conditions in the retina. Thus, theanti-Epo antibodies are expected to reduce the retinal pathology that isalso seen in patients with vascular retinal diseases such as wet AMD anddiabetic retinopathy.

Example 6 In Vivo Neutralization of Free EPO Example 6a In VivoNeutralization of Free EPO Using an Anti-Epo Fab

The in vivo activity and therapeutic efficacy of anti-EPO antibodieswere assessed in rabbit eyes as follows. Rabbits were dosedintravitreally with an anti-EPO Fab, NVS2 (1 mg/eye) and challenged withan intravitreal dose of EPO (3 ug/eye) four days later. Animals weresacrificed and ocular tissues including vitreous was extracted. Theamount of free EPO and total EPO in the vitreous was determined asdescribed below.

[Anti-EPO Fab] EPO Group mg/eye ug/eye 1 1 — 2 1 3

Total/Free EPO Levels:

Assays were performed using standard binding MSD plates (Meso-ScaleDiscovery, 384-well: MSD cat#L21XA), using coating buffer (PBS) andincubation buffer (PBS with 2% BSA (Sigma cat #A4503) and 0.1% Tween20and 0.1% Triton-X).

Capture antibodies were coated at 1 μg/ml in PBS (25 μl), and incubatedovernight at 4° C. Plates were washed 3× in wash buffer (PBS with 0.05%Tween20), and blocked with 25 μl incubation buffer at RT for 2 hrs.Plates were washed 3× in wash buffer. Vitreous dilutions in incubationbuffer were added to the plate (25 μl), and incubated for 60 min at RT.Human recombinant Darbepoietin was used as a standard (A000123, startingat 2 μg/ml). Plates were washed 3× in wash buffer. 25 μl primaryantibody was added (1 μg/ml in incubation buffer), and incubated at RTfor 60 min. Plates were washed 3× in wash buffer. 25 μl of anti-speciessecondary Sulfo-TAG antibodies were added (1:1000 in incubation buffer),and incubated at RT for 60 min. Plates were washed 3× in wash buffer,and 25 μl of 1× MSD Read buffer T was added (with surfactant, MSD cat#R92TC-1). Plates were read on a MSD Spector Imager 6000.

Total EPO Coat Antibody Epo-26 Clone 26G9C10 Primary Antibody Anti-EPOFab Secondary Antibody anti-human R32AJ-1 Vitreous Dilution 1:20-1:25Sensitivity 0.03 ng/ml Free EPO Coat Antibody Anti-EPO Fab PrimaryAntibody Epo-26 Clone 26G9C10 Secondary Antibody anti-mouse R32AC-1Vitreous Dilution 1:75-1:500 Sensitivity 1.6 ng/ml

Results and Conclusion:

The total EPO levels measured in the vitreous of animals injected withanti-EPO or vehicle was similar as expected (FIG. 2). In contrast, nofree EPO was measured in the vitreous of rabbits injected with anti-EPOFab, but average ˜100 ng/ml free EPO was measured in the vitreous ofrabbits injected with vehicle. Anti-EPO Fab administered intravitreallycompletely neutralized free EPO levels as expected.

Example 6b In Vivo Neutralization of Free EPO Using a Anti-Epo Fab

The in vivo activity and therapeutic efficacy of anti-EPO antibodieswere assessed in rabbit eyes as follows. Rabbits were dosedintravitreally with a pre-mixed solution of an anti-EPO Fab, NVS2 (1mg/eye) and EPO (3 ug/eye). Animals were sacrificed and ocular tissuesincluding vitreous was extracted. The amount of free EPO and total EPOin the vitreous was determined as described below. Note: Some eyesreceived a pre-mix solution of an anti-EPO Fab, EPO, and VEGF.

[Anti-EPO Fab] EPO VEGF Group mg/eye ug/eye ng/eye 1 — — 200 2 — 3 200 31 3 200 4 1 3 —

Total/Free EPO Levels:

Assays were performed using standard binding MSD plates (Meso-ScaleDiscovery, 384-well: MSD cat #L21XA), using coating buffer (PBS) andincubation buffer (PBS with 2% BSA (Sigma cat #A4503) and 0.1% Tween20and 0.1% Triton-X).

Capture antibodies were coated at 1 μg/ml in PBS (25 μl), and incubatedovernight at 4° C. Plates were washed 3× in wash buffer (PBS with 0.05%Tween20), and blocked with 25 μl incubation buffer at RT for 2 hrs.Plates were washed 3× in wash buffer. Vitreous dilutions in incubationbuffer were added to the plate (25 μl), and incubated for 60 min at RT.Human recombinant Darbepoietin was used as a standard (A000123, startingat 2 μg/ml). Plates were washed 3× in wash buffer. 25 μl primaryantibody was added (1 μg/ml in incubation buffer), and incubated at RTfor 60 min. Plates were washed 3× in wash buffer. 25 μl of anti-speciessecondary Sulfo-TAG antibodies were added (1:1000 in incubation buffer),and incubated at RT for 60 min. Plates were washed 3× in wash buffer,and 25 μl of 1× MSD Read buffer T was added (with surfactant, MSD cat#R92TC-1). Plates were read on a MSD Spector Imager 6000.

Total EPO Coat Antibody Epo-26 Clone 26G9C10 Primary Antibody Anti-EPOFab Secondary Antibody anti-human R32AJ-1 Vitreous Dilution 1:20-1:25Sensitivity 0.03ng/m1 Free EPO Coat Antibody Anti-EPO Fab PrimaryAntibody Epo-26 Clone 26G9C10 Secondary Antibody anti-mouse R32AC-1Vitreous Dilution 1:75-1:500 Sensitivity 1.6 ng/ml

Results and Conclusion:

The total EPO levels measured in the vitreous of animals injected withanti-EPO or vehicle were similar as expected (FIG. 3). In contrast, nofree EPO was measured in the vitreous of rabbits injected with ananti-EPO Fab, while on an average ˜200 ng/ml free EPO was measured inthe vitreous of rabbits injected with vehicle (FIG. 3). Presence of VEGFdid not appear to have any effect on either free or total EPO levelsmeasured. Anti-EPO Fab administered intravitreally completelyneutralized free EPO levels as expected.

1. An isolated antibody, or antigen binding fragment thereof, that bindsEpo with a K_(D) less than or equal to 50 pM.
 2. The isolated antibodyor antigen binding fragment of claim 1 that binds the Helix D domain ofEpo.
 3. The isolated antibody or antigen binding fragment of claim 1 orclaim 2 that further binds the Loop A-B domain of Epo.
 4. The isolatedantibody or antigen binding fragment of any of claim 2 or claim 3 thatfurther binds the Helix A domain of Epo.
 5. The isolated antibody orantigen binding fragment of any of the preceding claims wherein saidantibody binds human Epo.
 6. The isolated antibody, or antigen bindingfragment, of claim 1, that binds a conformational epitope comprisingamino acids within Epo Helix D and Loop A-B.
 7. The antibody, or antigenbinding fragment, of claim 6, that binds a conformational epitopefurther comprising amino acids within Epo Helix A.
 8. The isolatedantibody, or antigen binding fragment of claim 1 that binds aconformational epitope comprising amino acids at positions, 44-50, 52,53, 147, 150, 151, 154, 155, 159, and 162 of SEQ ID NO:
 81. 9. Theisolated antibody, or antigen binding fragment, of any of the precedingclaims, that binds a conformational epitope comprising amino acids atpositions, 9, 13, 44-53, 147, 150, 151, 154, 155, 158, 159, and 162 ofSEQ ID NO:
 81. 10. The isolated antibody, or antigen binding fragment,of any of the preceding claims, that binds a conformational epitopecomprising amino acids at positions, 23, 43-50, 52, 53, 131, 143, 147,150, 151, 154, 155, 159, and 162 of SEQ ID NO:
 81. 11. The isolatedantibody, or antigen binding fragment, of any of the preceding claimsthat also binds cynomologous, mouse or rat Epo.
 12. The isolatedantibody, or antigen binding fragment, of any of the preceding claimsthat further inhibits EPO-dependent cell proliferation with an EC₅₀ lessthan or equal to 350 pM.
 13. The isolated antibody, or antigen bindingfragment, of any of the preceding claims that inhibits EPO-dependentcell proliferation in B-cells expressing the EPO receptor.
 14. Anisolated antibody, or antigen binding fragment thereof, that binds thesame epitope as an antibody described in Table 1 or competes with anantibody described in Table
 1. 15. An isolated antibody, or antigenbinding fragment, of any of the preceding claims that binds EPO, andcomprises: a) heavy chain variable region HCDR1, HCDR2 and HCDR3 as setforth in SEQ ID NOs: 1, 2, and 3, respectively, and light chain variableregion LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NOs: 4, 5, and 6,respectively; b) heavy chain variable region HCDR1, HCDR2 and HCDR3 asset forth in SEQ ID NOs: 21, 22, and 23, respectively, and light chainvariable region LCDR1, LCDR2, and LCDR3 as set forth in SEQ ID NOs: 24,25, and 26, respectively; c) heavy chain variable region HCDR1, HCDR2and HCDR3 as set forth in SEQ ID NOs: 41, 42, and 43, respectively, andlight chain variable region LCDR1, LCDR2, and LCDR3 as set forth in SEQID NOs: 44, 45, and 46, respectively; or d) heavy chain variable regionHCDR1, HCDR2 and HCDR3 as set forth in SEQ ID NOs: 61, 62, and 63,respectively, and light chain variable region LCDR1, LCDR2, and LCDR3 asset forth in SEQ ID NOs: 64, 65, and 66, respectively.
 16. The isolatedantibody, or antigen binding fragment, of any of the precedinglcaimiclaims comprising heavy and light chain variable regions havingamino acid sequences at least 90% identical to SEQ ID NOs: 13 and 14;SEQ ID NOs: 33 and 34; SEQ ID NOs: 53 and 54; or SEQ ID NOs: 73 and 74,respectively.
 17. The isolated antibody, or antigen binding fragment, ofany of the preceding claims that binds Epo comprising a heavy chain anda light chain with an amino acid sequence having at least 90% sequenceidentity to SEQ ID NO: 15 and 16, 35 and 36, 55 and 56, or 75 and 76.18. The antibody or antigen binding fragment of any of the precedingclaims, wherein said antibody is a human antibody, a chimeric antibody,a monoclonal antibody, a single chain antibody, Fab, Fab′, F(ab′)2, Fvor scFv.
 19. The antibody or antigen binding fragment of any of thepreceding claims, wherein said antibody is an IgG isotype.
 20. Anisolated nucleic acid molecule comprising a nucleotide sequence encodingthe antibody or fragment as claimed in any of the preceding claims. 21.The nucleic acid molecule of claim 20, wherein said nucleic acidcomprises a sequence encoding a heavy chain variable domain and saidsequence has at least 95% sequence identity to a sequence selected fromSEQ ID NOs: 17, 37, 57, and
 77. 22. The nucleic acid molecule of claim20 wherein said nucleic acid comprises a sequence encoding a light chainvariable domain and said sequence has at least 95% sequence identity toa sequence selected from SEQ ID NO: 18, 38, 58, and
 78. 23. A vectorcomprising the nucleic acid molecule of any of claims 20 to
 22. 24. Anisolated host cell comprising the nucleic acid as claimed in any ofclaims 20 to 22 or the vector of claim
 23. 25. A composition comprisingthe antibody or antigen binding fragment of any of claims 1 to 19 and apharmaceutically acceptable diluent or carrier.
 26. A method of treatingretinal vascular disease in a subject comprising administering to saidsubject, an effective amount of a composition comprising the antibody orantigen binding fragment of any of claims 1 to
 19. 27. The method ofclaim 26, wherein the retinal vascular disease in the subject isassociated with a disease or condition selected from: diabeticretinopathy, diabetic macular edema, proliferative diabetic retinopathy,non-proliferative diabetic retinopathy, age-related maculardegeneration, retinal vein occlusion, multifocal choroiditis, myopicchoroidal neovascularization, and retinopathy of prematurity.
 28. Amethod of treating macular edema in a subject comprising administeringto said subject, an effective amount of a composition comprising theantibody or antigen binding fragment of any of claims 1 to
 19. 29. Amethod of treating diabetic retinopathy in a subject comprisingadministering to said subject, an effective amount of a compositioncomprising the antibody or antigen binding fragment of any of claims 1to
 19. 30. A method of treating diabetic macular edema in a subjectcomprising administering to said subject an effective amount of acomposition comprising the antibody or antigen binding fragment of anyof claims 1 to
 19. 31. A method of treating proliferative diabeticretinopathy, comprising contacting EPO with a composition comprising theantibody or antigen binding fragment of any of claims 1 to
 19. 32. Amethod of inhibiting EPO-dependent cell proliferation, comprisingcontacting EPO with a composition comprising the antibody or antigenbinding fragment of any of claims 1 to
 19. 33. A method of inhibitingEPO-dependent cell proliferation in a cell expressing an Epo receptor,comprising contacting said cell with a composition comprising theantibody or antigen binding fragment of any of claims 1 to
 19. 34. Themethod of claim 33 wherein the cell is a B-cell.
 35. A method ofinhibiting diabetic macular edema, comprising administering to the eyeof a subject a composition comprising the antibody or antigen bindingfragment of any of claims 1 to 19, wherein administration of saidcomposition decreases retinal vein dilation, decreases vascular leakageand/or increases blood flow in the eye.
 36. A method of inhibiting EPObinding to the EPO receptor on a cell, comprising contacting EPO with acomposition comprising the antibody or antigen binding fragment of anyof claims 1 to
 19. 37. The method of claim 36 wherein the cell is in asubject.